Innovative Chitosan Coatings for CR-39 Lenses - Centro Escolar University

CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila Innovative Use of Chitosan Powder in Developing Eco-Friendly Scratch-Resistant Coatings for CR-39 Ophthalmic Lens A Thesis Presented to the Faculty of School of Optometry Centro Escolar University Submitted by: Bello, Althea Faye Eustaquio, Justin Gabrielle Francisco, Jesus Aviel Ingal, Danica Ishi Ragas, Christine Joy Umila, Jarra Bedhel Zarco, Stephanie Allyson Submitted to: Dr. Carol A. Gariando CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila INTRODUCTION Ophthalmic lenses, widely used to correct refractive errors, have evolved beyond simple vision correction tools to include advanced features such as UV protection, blue light filtration, and scratch resistance. However, the growing demand for more sustainable and environmentally friendly products in the optical industry has prompted researchers to explore bio-based materials for lens coatings. Traditional coatings, typically made from synthetic polymers, often contribute to environmental waste and may involve complex, non-biodegradable components. In light of this, natural alternatives such as chitosan, a polysaccharide derived from chitin found in the shells of crustaceans and insects, have garnered significant attention. Chitosan is a natural polysaccharide, composed of randomly distributed β-(1-4) linked D-glucosamine and N-acetyl-D-glucosamine, obtained by deacetylation of the exoskeletons of crustaceans such as shrimp and crabs and fungal cell walls, which is the second most abundant biopolymer (Frank et al., 2019). The range of applications for biopolymers has broadened with the demand for environmentally friendly materials in innovation. Chitosan has highlighted its biopolymer properties and researchers have actively pursued the development of various chitosan derivatives to introduce innovative functions or properties of the material, particularly in biomedical and ophthalmics applications. Studies demonstrated that chitosan coating can reduce bacterial adhesion, eliminate the fogging effect, and UV protection on ophthalmic lenses (Aljibori 2023). As sustainability becomes a priority for both manufacturers and consumers, the use of bio-based coatings like chitosan represents a potential breakthrough in creating ophthalmic products that are both functional and environmentally responsible. CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila This research aims to explore the effectiveness of chitosan-based coatings on CR-39 lenses, a popular plastic lens material known for its lightweight and impact-resistant properties. The study will focus on chitosan's ability to provide scratch resistance, its potential to reduce environmental impact, and its overall suitability as an alternative to traditional synthetic coatings. To address the research gap, this study will conduct extensive field testing of chitosan-treated lenses, specifically CR-39, under various environmental conditions to assess long-term durability, chemical resistance, optical clarity, and compatibility with other lens coatings. By focusing on chitosan’s ability to provide a sustainable, scratch-resistant coating, the research aims to identify potential challenges, such as surface modifications, moisture sensitivity, and polymer crosslinking. Additionally, the study will evaluate chitosan’s environmental impact, including its biodegradability and non-toxicity, compared to traditional coatings. A comparative analysis will be conducted to assess the performance differences in terms of durability, clarity, and chemical resistance, as well as the scalability and cost-effectiveness of manufacturing chitosan-based coatings. Ultimately, the goal is to promote a more sustainable ophthalmic industry and unlock new market opportunities for chitosan as an eco-friendly alternative. CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila BACKGROUND OF THE STUDY The increasing demand for ophthalmic lenses, particularly CR-39 lenses, has led to the development of coatings that enhance durability and optical performance, particularly in terms of scratch resistance. CR-39, a widely used plastic resin in lenses, offers lightweight and optical benefits but is prone to scratches without protective coatings. However, traditional coatings made from synthetic materials like polyurethane or silica-based compounds, provide protection but pose significant environmental concerns due to their non-biodegradable nature and harmful byproducts. As sustainability becomes a growing priority, there is a need for eco-friendly alternatives that offer comparable or superior performance. Chitosan, a natural biopolymer derived from the exoskeletons of crustaceans, has emerged as a promising candidate. With its biodegradable, non-toxic, and adhesive properties, chitosan offers potential as a sustainable solution for scratch-resistant coatings on CR-39 lenses. Exploring the potential of chitosan-based coatings can help address both the environmental and functional limitations of synthetic materials, particularly for CR-39 lenses. As this industry has significant waste output from product manufacturing, environmental responsibility is essential (Gheorghe, 2023). Concerns over the escalation of ecological consequences are consistent with these actions. Due to this, the need for eco-friendly materials in innovative biopolymers has found more uses (Aljibori, 2023). CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila Various studies have highlighted chitosan's potential in creating protective coatings for different surfaces, showing its ability to increase resistance to wear and tear. It has also demonstrated its use in various fields, including biomedical applications, environmental protection, and material engineering. For instance, Zhou et al. (2022) developed superhydrophobic chitosan-based coatings that exhibited enhanced durability, while Zhang et al. (2021) focused on the chemical modification of chitosan to improve its mechanical properties. Studies have also shown that chitosan-based coatings have developed good adhesion properties and corrosion resistance which widened their range of applications. Mansoor et al. (2022) explored a dual-functional chitosan (polysaccharide)-based coating with hydrophilic properties. Additionally, chitosan has also been investigated for potential use in various applications due to its biocompatibility. Aljibori et al. (2023) assessed the performance of chitosan in various lens applications, including its effectiveness in coatings, durability, and comfort. The effectiveness of utilizing chitosan with chemical additives and cross-linkers to increase mechanical properties has also been demonstrated. As it is is generated from chitin, a natural polymer found in the exoskeletons of crustaceans such as shrimp and crab, it is common in nature, and its chemical change into chitosan usually entails deacetylation, which eliminates acetyl groups and transforms it into a more reactive form. As a result, chitosan is a renewable, widely available resource that supports sustainable material development. Furthermore, glutaraldehyde-cross-linked chitosan delivers much stronger and more durable coatings compared to non-cross-linked chitosan and has applicability in an area where strength is required for longevity, such as for usage in lens coatings (Pinto et al.,2019). Meanwhile, Smith CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila et al. (2021) examined the use of glycerol to plasticize chitosan. Glycerol destroys hydrogen bonds and even strengthens intermolecular contacts, which helps to improve the flexibility and mechanical properties of chitosan-based films. The use of synthetic materials for the same purpose is showing poor long-term environmental performance. Examples include polyurethane, which is used in various optical and protective coatings due to its durability, flexibility, and resistance to abrasion. According to Sonnenschein and Wendt (n.d.), there are sustainability issues with polyurethane, as it is a toxic isocyanate substance and is non-biodegradable. Moreover, chitosan is a naturally occurring substance that degrades biologically. When used in coatings and packaging, it decomposes into innocuous byproducts, minimizing its influence on the environment. Due to its adaptability, chitosan can be used in many different contexts, which makes it a valuable resource for a broad range of industries. Its widespread recognition as a non-toxic substance also makes it more suitable for use in sectors where consumer safety is a top issue, such as the food, pharmaceutical, and cosmetics industries. However, there has been limited research specifically on applying chitosan for scratch-resistant coatings in the optical industry, particularly for ophthalmic lenses. Most studies have centered on chitosan's use in adhesives, medical devices, and corrosion-resistant materials, leaving a significant gap in understanding its role in lens coatings CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila The researchers will focus on developing sustainable, chitosan-based anti-scratch coating for CR-39 ophthalmic lenses. This research aims to explore the mechanisms behind the beneficial properties of chitosan and how these properties contribute to the overall performance of the coatings. Furthermore, chitosan's effectiveness will also be assessed, in terms of its scratch-resistant coating capability while considering factors such as durability, adhesion, film-forming properties, and biodegradability. Despite promising findings regarding chitosan’s properties, limited research has focused on its use in scratch-resistant coatings, with most studies concentrating on its applications in adhesives and medical devices. Further research is needed to optimize chitosan's use, including enhancing scratch resistance, assessing long-term performance, optimizing formulations, lens clarity, and developing scalable production methods. Addressing these gaps could contribute to the development of high-performance, eco-friendly chitosan-based adhesives and coatings for the ophthalmic industry. CONCEPTUAL FRAMEWORK CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila This conceptual framework presents a systematic approach to developing an eco-friendly, scratch-resistant coating for CR-39 ophthalmic lenses, using chitosan powder as the primary material. The inputs include essential elements such as raw materials (chitosan, solvents, and lens substrates), laboratory equipment (for coating, mixing, curing, and testing), lab procedures, coating techniques, and resistance tests. The process highlights several key stages: formulation of the coating, coating application, optimization of the formula for enhanced performance, and rigorous testing for scratch resistance. These steps ensure a well-rounded approach, combining material science with eco-conscious innovation. The output aims to produce a high-quality, sustainable coating that not only protects lenses from scratches but also reduces environmental impact. This research framework demonstrates a balance between technological advancement and ecological responsibility in creating ophthalmic products. THEORETICAL FRAMEWORK Many traditional ophthalmic lens coatings rely on chemicals and solvents which are commonly synthetic. Over time, these may contribute to the accumulation of wastes that are harmful to the environment. This study examines the use of biopolymers like chitosan as a scratch-resistant coating for ophthalmic lenses. Biopolymers, like chitosan, are gaining prominence in the material sciences because of their sustainability and adaptability. Chitosan is a bio-based material widely used in sustainable production across various industries. Its biodegradability, biocompatibility, and non-toxic nature make it suitable for eco-friendly and sustainable applications (Amitaye et al., 2024). Chitosan powder can be used as a raw material to create formulations for anti-scratch coating which increase the polymer's mechanical CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila strength. Chitosan has become an important component due to its strong adhesive properties, capable of forming a protective layer that creates a barrier, reducing susceptibility to scratches in ophthalmic lenses. This study employs surface engineering principles to enhance the interactions between chitosan and lens materials, focusing on improving the adhesion and durability of chitosan-based coatings for effective protection against abrasion and wear. By utilizing advanced surface engineering techniques, the research aims to boost the performance of these coatings, creating a robust solution for ophthalmic lenses. Through innovative manufacturing processes and careful formulation optimization, the study seeks to develop high-performance coatings that fulfill modern demands for functionality and environmental sustainability. Chitosan’s capacity to improve through chemical modifications meets the demand for coatings that provide durability and resistance to everyday wear. This makes it a potential material for developing ophthalmic coatings that may offer enhanced and sustainable scratch-resistance coating. OBJECTIVES OF THE STUDY General The aim of the study is to contribute to the development of environmentally sustainable solutions in the field of ophthalmic lens coatings by utilizing biodegradable and non-toxic materials. It will test the adhesion properties of the chitosan coating on various lens materials to measure durability under different environmental conditions and assess that the optical clarity of ophthalmic lenses is maintained after the application of the chitosan-based coating. CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila Specific 1. To determine the ability of chitosan powder to produce scratch-resistance coating. 2. To formulate and optimize a chitosan-based coating and evaluate its effectiveness in enhancing lens performance. 3. To test the coated lenses under various conditions including heat and and extensive wiping, to determine the adhesion quality and durability of the chitosan coating HYPOTHESIS OF THE STUDY Null Hypothesis (Ho): Chitosan Powder is not an effective material in scratch resistance coatings for CR-39 Ophthalmic Lenses. Alternative Hypothesis (Ha): Chitosan Powder is an effective material in scratch resistance coatings for CR-39 Ophthalmic Lenses. ASSUMPTIONS OF THE STUDY 1. The researchers assumed that all the CR-39 lenses in the study were the same in size, material, and surface condition prior to applying the scratch-resistant coating 2. The researchers assumed that the application of the scratch-resistant coating on CR-39 lenses was performed consistently and uniformly across all samples. 3. The researchers assumed that the commercially available chitosan powder used in the formulation was of consistent quality throughout. CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila SIGNIFICANCE OF THE STUDY This study may benefit the Department of Environment and Natural Resources (DENR), Bureau of Fisheries and Aquatic Resources (BFAR), fishermen/fisheries, optical laboratories, optometrists, material suppliers, manufacturing industry workers, and future researchers. For the Department of Environment and Natural Resources. This study will help them to promote protocols that include waste management, eco-friendly alternatives, and reduction of marine and coastal pollution. By demonstrating the use of chitosan in ophthalmic lenses, it will raise public awareness of the importance of this material, reinforcing DENR’s efforts to advocate for eco-friendly consumer choices and to minimize environmental footprint. For the Bureau of Fisheries and Aquatic Resources (BFAR). This study will support the department’s initiative to manage marine resources sustainably by encouraging fisheries to utilize seafood byproducts instead of discarding them. For the Fishermen/fisheries. This study will help them to provide an additional livelihood by creating a demand for chitosan; this seafood waste will be viewed as a valuable commodity. Also, this may contribute to more sustainable fishing practices and reduce the environmental footprint of the seafood industry. For the Optical Laboratories. This study will highlight the importance of replacing non-biodegradable materials with sustainable chitosan-based coatings, thereby reducing waste CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila production and improving environmental impact. Implementing these practices can enhance the reputation of laboratories as leaders in sustainability. For the Optometrists. This study will provide insights into how adopting sustainable materials can align with their commitment to patient care and public health. By integrating eco-friendly practices, optometrists can contribute to a healthier environment while meeting growing consumer expectations for sustainability. For the Material Suppliers. This study will help the suppliers of chitosan or seafood waste establish relationships with lens manufacturers seeking sustainable materials, creating a demand for eco-friendly products within the supply chain. For the Manufacturing Industry Workers. This study will help in improving working conditions where workers will be handling non-toxic, eco-friendly materials rather than being exposed to traditional, synthetic coatings. For the Future Researchers. This study will serve as a valuable resource on sustainable practices in optical laboratories and their impact on environmental health. It may inspire further investigations into innovative materials and methods that enhance sustainability within the optometry field. CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila LIMITATIONS AND DELIMITATIONS LIMITATIONS This study may encounter several limitations that could affect its findings. One significant limitation is the sampling technique where the selected CR-39 lenses may not comprehensively represent an entire market, which could restrict the generalizability of the results. Additionally, the reliance on laboratory testing to assess scratch resistance may not fully reflect real-world conditions, as factors such as user handling and varying environmental contexts could substantially influence lens durability. Furthermore, the accuracy of the instruments employed to measure scratch resistance and optical clarity may introduce variability, potentially impacting the overall reliability of the results. DELIMITATION This study focuses specifically on CR-39 lenses to assess the potential of chitosan-based coatings in ophthalmic applications. It limits its scope to chitosan powder without other biopolymers or chemical modifications and evaluates only key performance indicators: scratch resistance, optical clarity, adhesion, and durability, omitting added functionalities like blue light filtration. Glutaraldehyde is the sole cross-linking agent, and testing is confined to controlled conditions rather than real-world, long-term exposure. These delimitations ensure a focused analysis of chitosan’s potential as an eco-friendly scratch-resistant coating for CR-39 lenses. CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila DEFINITION OF TERMS To ensure clarity and a comprehensive understanding of the technical aspects of this research, the following terms are defined: Adhesion - The ability of different substances to adhere to one another. Bio-based - A material produced using substances derived from living organisms. Biocompatibility - The ability of a material to interact with a biological system without causing harmful effects. Biodegradability - The ability for a material to be broken down naturally by the organisms in an ecosystem. Biomedical - Used to describe the relation of the activities and applications of science to clinical medicine. Biopolymer - Materials that have been manufactured from biological sources such as fats, vegetable oils, sugars, resins, and proteins. CR-39 lenses - A type of plastic lens material known for its impact resistance and optical clarity. Chemicals - Any substances with a defined composition. Chitin - A cationic and biodegradable polymer, found mainly in crustacean shells. Chitosan - A polysaccharide derived from chitin. Cross-linkers - The molecule that is employed to create this connection Cross-linking - The process of chemically joining two or more molecules by a covalent bond. Deacetylation - The process of elimination of an acetyl group(s) from organic compounds and transforming into a more reactive form. Glutaraldehyde - An organic compound with a chemical name of C5H8O2 that contains two aldehyde groups CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila Glycerol- It is a colorless, odorless, syrupy, sweet liquid, with a chemical name of C3H8O3 that is usually obtained by the saponification of natural fats and oils, which destroys hydrogen bonds and strengthens intermolecular contacts. Hydrophilic - Having a strong affinity for water, wherein hydrophilic molecules get absorbed or dissolved in water. Hydrophobic - Resistant to water, meaning it has the ability to repel water. Innocuous - Not harmful or dangerous. Plasticizers - A low molecular weight substance added to a polymer solution to promote its plasticity and flexibility. Polysaccharide - A carbohydrate that can be decomposed by hydrolysis into two or more molecules of monosaccharides. Polyurethane - A synthetic resin compound composed of urethane groups linked to polymer units. Silica-based compounds - A synthetic material containing silicon and oxygen. Solvents - A substance that is capable of dissolving one or several substances. Susceptibility - The degree to which a material is affected by a particular agent or condition. CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila CHAPTER 2 Related Study and Literature This chapter comprises related literature and studies which have served as guide and foundational support towards this research. Chitosan in Enhancing Coating Performance The integration of chitosan in enhancing coating performance has been explored through various innovative approaches, showcasing its potential for creating advanced materials with superior properties. Zhou et al. (2022) presented a facile method for processing durable and sustainable superhydrophobic chitosan-based coatings derived from waste crab shells. Their research involved binding the amines of chitosan with a long-chain polymer, octadecylamine, using a cross-linking agent (glutaraldehyde). The resultant coating was found to transform an ordinary hydrophilic polyurethane sponge into a superhydrophobic and superoleophilic absorbent. This absorbent demonstrated the capacity to rapidly absorb and separate various organic solvents and oils, showcasing a significant improvement in functionality and applicability. The study also highlighted the ability of chitosan to form multifunctional coatings that exhibit durability and scratch resistance, crucial for protective applications. This aspect is particularly relevant for developing high-performance coatings, such as those used for lens protection, where the enhancement of durability is essential. Aguilar-Ruiz et al. (2023) studied chitosan-based coatings to prevent aluminum CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila corrosion in seawater. Developed by dissolving chitosan in an acidic solution with additives, these coatings were applied to aluminum substrates and tested using electrochemical methods and immersion in seawater. The results showed effective corrosion protection, with additives like graphene oxide improving barrier properties and resistance. The coatings exhibited strong adhesion, stability, and minimal degradation, outperforming some commercial inhibitors. While eco-friendly and promising as sustainable alternatives, further research is needed to understand their scratch resistance and durability, enhancing their potential in marine applications. The study also highlighted the potential of these eco-friendly coatings to serve as sustainable alternatives to traditional materials. However, there is limited understanding of how chitosan-based adhesives contribute to scratch resistance and durability. Future research should explore the mechanisms by which chitosan improves these properties, as well as the overall performance of the coatings in resisting physical damage such as scratches and wear. Tagliaro et al. (2022) developed solvent- and fluorine-free chitosan-based coatings with tunable transparency and superhydrophobicity by modifying chitosan with stearoyl chloride. Techniques such as spray, dip, and spin coating, followed by thermal treatment, enhanced adhesion and cross-linking. The degree of derivatization was precisely controlled, allowing customization of transparency and achieving high water contact angles for superhydrophobicity. While the study demonstrated the effectiveness of stearoyl derivatization in creating sustainable coatings, the researchers noted limitations in durability and longevity and called for further studies to assess performance under diverse environmental conditions and on a wider range of substrates. A study by Mansoor et al. (2022) developed a dual-functional chitosan-based coating for CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila optical devices, combining polysaccharides and mesoporous silica nanoparticles (MSN). Applied via a simple one-pot technique, the hydrophilic coating prevents fogging and inhibits microbial growth without compromising lens optical properties. Low-field nuclear magnetic resonance (LF-NMR) analysis showed strong chitosan-MSN interactions that enable water trapping within the coating, achieving a 95% success rate in fog and microbial inhibition. Tests, including hot/cold fogging and plate counts, emphasized the importance of bound water for functionality, though durability was not explored, focusing solely on immediate anti-fogging and antimicrobial effects. Aydemir et al. (2021) investigated chitosan, gelatin, silica-gentamicin, and bioactive glass coatings to improve the performance of orthopedic metallic implants. Two coatings were studied: one for temporary implants, using a chitosan/gelatin layer with silica-gentamicin nanoparticles on stainless steel, and another for permanent implants, featuring a two-layer system on titanium with a bioactive hybrid layer and a gelatin/chitosan-silica-gentamicin layer. The coatings, applied via spraying and electrophoretic deposition, offered bioactive and antibacterial properties, cost-effectiveness, and uniformity. The findings highlighted that stainless steel and titanium implants could benefit from bioactive and antibacterial systems that were both cost-effective and easy to produce using techniques like spraying and electrophoretic deposition. Moreover, the uniform and homogeneous coatings provided by the chitosan and gelatin layers acted as excellent carriers for silica-gentamicin nanoparticles. However, their long-term stability under physiological conditions remains untested, raising concerns about durability over time. The series of studies reviewed highlight the significant advancements in developing CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila chitosan-based coatings for diverse applications, from superhydrophobic and corrosion-resistant surfaces to antimicrobial and orthopedic-friendly films. These coatings show considerable potential in protective applications, enhancing material properties such as wear resistance, optical clarity, and microbial protection. However, key research gaps remain, particularly concerning the long-term durability, environmental impact, and broader applicability of these technologies. Future research should focus on addressing these limitations, investigating how chitosan coatings perform in varied environmental conditions, and exploring their full potential in medical and industrial contexts. Adhesive and Cohesive Capabilities of Chitosan Chitosan is a versatile biopolymer obtained by the deacetylation of chitin, which has attracted significant interest due to its unique properties such as biodegradability, biocompatibility, nontoxicity, and antibacterial activities. Abundantly found in nature within crustacean shells, insect cuticles, and fungal cell walls, chitosan's adhesive and cohesive properties have been considered an alternative to traditional, petroleum-based adhesives. Nowadays, chitosan becomes particularly promising in a wide range of applications due to environmental awareness and societal requirements for an environmentally friendly alternative to synthetic materials. It highlights the adhesive properties of chitosan, bridging structural, chemical, and functional knowledge in pursuing pressing environmental needs and facilitating sustainable adhesive solutions. One of the most prevalent biopolymers in the world, chitosan is a deacetylated form of chitin that is made up of (1 → 4)-D-glucosamine (GlcN) residues. Chitin, or (1 → 4)-N-acetyl-D-glucosamine (GlcNAc), is found in a variety of natural materials, including the CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila exoskeletons of crustaceans, insect cuticles, fungal cell walls, and algae. Biodegradability, biocompatibility, non-toxicity, antibacterial activity, and adhesion are some of the crucial properties of chitosan. It is therefore widely used in many different industries, such as medicine, food packaging, textiles, agriculture, cosmetics, and even as a support for enzymatic immobilization. Chitosan (CHIT) is a promising polysaccharide for use in adhesive applications. These days, environmental concerns are receiving more and more attention, and a major worry is the over-reliance on petroleum resources. There is an urgent need to switch from fossil fuel-based to bio-based materials quickly because of the irreversible effects of climate change.Many adhesives include hazardous ingredients that are bad for the environment and people's health. Furthermore, a considerable risk of fire events arises from the flammability of the majority of them. Sustainable alternatives are urgently needed due to the escalating environmental problems with petroleum-based adhesives. Recently, an adhesive for paper bonding was proposed that is made from starch and lignosulphonate and crosslinked with laccase. Epoxidized kraft lignin in the form of lignin nanoparticles and biocolloids has resulted in a new glue that is as strong as conventional wood adhesives. The objective of this research is to create a new adhesive based on chitosan that has better qualities (Costa et. al., 2024). According to study by Noto et al., the amino groups do in fact have a favorable impact on the chitosan adhesive strength. (Abdelmoula et. al., 2021). According to Xi et al., in 2022. Chitosan, for instance, is a biomass substance that has a lot of reserves. In order to create an environmentally safe wood adhesive, it was utilized in this project. Petroleum-based aldehydes were removed because of their toxicity, volatility, and CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila unsustainability by using special oxidation-modified starch, glucose, and sucrose as hardeners. Chitosan is used as a thickening agent to increase viscosity in food processing and has been shown to have benefits on decreasing blood sugar and cholesterol levels. Because of its exceptional film-forming capabilities, it has been widely used in membranes, a functional use that has been the subject of numerous research studies. Chitosan adhesives have mostly been tested for use as wound dressings in medical procedures because of their biological safety properties. Nevertheless, the wood industry hardly ever uses chitosan as an adhesive. Its high viscosity and poor solubility may be the primary causes of this. In the past, chitosan-phenolic systems were studied as wood adhesives, using laccase, a phenolic compound, and chitosan as basic ingredients together. The phenolic compounds' chemical structures, the laccase's relative oxidation rates of the compounds, and the viscosity that forms can all be linked to this adhesive's strong bonding properties. This study concludes that chitosan has a wide range of applications. Chitosan is a naturally occurring polymer that is generated by deacetylating chitin and is found in many places, including the shells of insects, shrimp, and crabs. Because environmental issues have gotten worse recently. Consumers are looking for environmentally responsible substitutes, and chitosan is a perfect choice. In addition, chitin and chitosan have unique properties such as being non-toxic, biocompatible, and biodegradable. Researchers discovered that chitosan is an excellent adhesive alternative due to its composition and structure. However, investigations have discovered that chitosan has low water resistance; consequently, researchers from various studies experimented with substituting the amine functions of chitosan in order to improve it. According to studies, amino groups and treating 8 mass percent of oxidized starch with a chitosan solution at room temperature improve chitosan adhesive strength. Chitosan can also CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila be used in a variety of ways, according to studies, including the production of particleboard and chitosan nanofibers. These tests have demonstrated that chitosan's physical and chemical properties, as well as its uses in the food, environmental, and medical industries, allow it to be employed in a variety of ways. Chitosan as a Transformative Binder in Next-Gen Applications Chitosan is emerging as a potential material in different fields because of its unique properties. The said natural biopolymer is biodegradable and compatible, mechanically strong, and can be applied in several industrial fields including adhesives, coatings, and biomedical devices. It is obtained from renewable resources and presents as a strong candidate for replacing synthetic materials in optical applications. With sustainability becoming a central part of the material sciences, chitosan presents the potential for developing environmentally friendly coatings that meet the goals of global efforts to reduce environmental impact without compromising functionality. In the area of ophthalmic lenses, chitosan-incorporated coatings offer a multifaceted answer to longstanding problems. Lenses were subjected to environmental and mechanical stresses and coatings with intrinsic durability also had to withstand optical clarity under conditions of variability. Recent studies by Aljibori et al. 2023 showed the strengths in chitosan-starch composites in applications of lens coatings for they exhibited enhancements in scratch resistance, toughness, and moisture retention. These attributes would be required for the durability and practicality of lenses, especially for users who rely on them to correct vision CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila day-to-day. Xi et al. (2022) studied the possibility of using chitosan in making biodegradable adhesives and focused on its blending with oxidized carbohydrates. In this paper, varying proportions of chitosan were blended with oxidized glucose, sucrose, and starch to prepare adhesives whose bonding ability on plywood was investigated. The strong chemical bonding as a result of chitosan indicates its effectiveness in enhancing scratch resistance and durability in coatings. Ophthalmic lenses, therefore, represent valuable products to which this product can be added. Moreover, the fact that the adhesives are water-resistant could directly mean an enhancement in the performance of the lens coatings, which often suffer from factors such as humidity and temperature changes. In 2023, Aljibori et al, as part of efforts to make ophthalmic lenses more sustainable, functionally, and durable, discussed the potential application of using a chitosan-starch composite. Cross-linking starch with chitosan resulted in a stable network structure, significantly improving lens durability and scratch resistance. Despite such structural improvements, composites retained their important properties like biocompatibility and moisture retention that had ensured their suitability for extended usage with lenses. It also caused less fogging, and lenses remained much longer than routine wear and tear. In both Aljibori et al. (2023) and Xi et al. (2022), mechanisms of cross-linking were found to be crucially important. Liu et al. indicated that oxidation led to improved adhesive strength in chitosan due to the formation of robust chemical bonds. Aljibori et al. similarly utilized chemical CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila cross-linking for stabilization of the chitosan-starch composites to ensure scratch resistance and durability. This general reliance on cross-linking brings to the fore the flexibility of the chitosan material to be chemically modified towards different needs of applications. Chitosan, therefore, in this sense, signifies a material that embodies the principles of being eco-friendly, performance-oriented, and innovative. This makes it a potentially suitable substitute for conventional materials; without compromising functionalities, it can be used in next-generation products be it medical devices, agricultural tools, packaging, or optical lenses. Chitosan would still play a huge role in molding a sustainable future. Chitosan Used for Material Strength and Chemical Efficiency Chitosan’s intrinsic properties and molecular structure yield high tensile strength and form a composite coating that enhances the structural stability of ophthalmic lenses. The functionalization of Chitosan with certain aldehyde groups refines its durability and adhesion tendencies, with the incorporation of cross-linking agents that ensure optical clarity without compromising the quality. Based on the study of Cintron‐Cruz et al. (n.d.), Chitosan can facilitate brisk and tough adhesion to surfaces, even in the absence of covalent bond formation, which makes it chemically efficient as a material. It also renders conductive ophthalmic applications since Chitosan is stable in aqueous environments, and has a great resistance to mechanical abrasion. According to the study of Wang, J., & Zhuang, S. (2022), Chitosan is a natural biopolymer with an adjustable structure and abundant function groups. Furthermore, it can be CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila processed into various shapes and sizes, making it suitable for several applications. Over the last years, several attempts have been made to replace petrochemical products with renewable and biodegradable components as a promising hybrid material.. Naturally occurring polymers chitin represent interesting candidates for replacing synthetic products and could reduce the dependency and have a positive impact on the environment (Azmana et al., 2021). Chitosan is also a remarkable bio-based polymer with excellent intrinsic properties, it is known for its antimicrobial and film-forming properties and has huge potential for high mechanical strength and good thermal stability. Several chitosan-based bionanocomposites with enhanced physical and chemical properties have been created as an economical and environmentally beneficial method by applying nanotechnology to chitosan-based materials. Several techniques are employed to synthesize chitosan-based bionanocomposites, including solution casting, a method for creating films or coatings that involves dissolving chitosan in an acidic solution and then combining it with nanoparticles, (Aljibori et al., 2023). In Polymerization, a nanocomposite matrix is created by introducing nanoparticles into the polymerization process. Porous structures are made via freeze-drying, particularly for tissue engineering and medication delivery. Enhancing Scratch Resistance and Surface Durability with Chitosan Chitosan, a natural polysaccharide derived from chitin, has gained increasing attention in recent years due to its versatile properties, including biodegradability, non-toxicity, and biocompatibility. These characteristics make it a suitable candidate for various applications, and CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila a safer alternative to conventional coating, especially in coating technology. Researchers have been exploring chitosan-based coatings for their ability to improve surface durability, scratch resistance, and functionality, especially in industries such as packaging, electronics, and medical devices. With chitosan’s ability to form films that enhance the mechanical properties of substrates, it has driven interest in its use as a protective coating material. One of the key strategies for enhancing chitosan’s performance in coatings is through modification, which improves its surface properties. Recent studies have demonstrated the growing potential of chitosan-based coatings in various applications due to their versatile properties, including hydrophobicity, transparency, and antimicrobial activity. Tagliaro et al. (2022) proposed a sustainable, fluorine-free approach by modifying chitosan with fatty acid side groups through stearoyl derivatization. Their study highlighted the improvement in scratch resistance and surface durability. The modification process was carried out using a solvent-free deposition method, which avoids the use of harmful chemicals and solvents. The study demonstrated excellent abrasion resistance, with a contact angle of 150° and a roll-off angle of 144°, indicating its effective water-repellent properties. The researchers found that the introduction of stearoyl groups on chitosan not only increased hydrophobicity but also contributed to the scratch resistance of the coating. Their coatings exhibited strong durability when exposed to harsh conditions such as abrasion, water, and acidic environments. This ability to maintain surface integrity under stress makes chitosan an ideal candidate for coatings requiring enhanced surface durability. This combination of high hydrophobicity and mechanical strength made the modified chitosan coatings more resistant to external stresses, thereby enhancing surface longevity. CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila In addition to hydrophobic coatings, other studies have explored chitosan’s potential in multifunctional coatings. Scratch resistance is an important property for coatings used in high-contact and wear-prone environments and superhydrophobic chitosan coatings are particularly valuable in reducing surface degradation, as water and other corrosive substances are less likely to come into contact with the substrate. Li et al. (2022) focused on the development of a dual-functional chitosan-based coating for optical devices highlighting the role of chitosan in improving scratch resistance. Their study demonstrated that chitosan coatings could be modified to achieve enhanced mechanical properties, including greater scratch resistance, without compromising transparency or functionality. These improvements were particularly useful for optical devices that need to maintain both durability and clarity. By adding specific functional groups and using cross-linking agents, chitosan coatings showed significant improvement in surface hardness and scratch resistance. The study highlighted the coating’s ability to prevent fog accumulation without compromising the scratch resistance or transparency of the surface, further enhancing its longevity. While their focus was on the dual functionality of antifogging and antimicrobial effects, they also found that the chitosan coatings contributed to the surface durability of optical materials. This suggests that chitosan’s natural properties can not only improve surface performance but also offer protection from external stresses, which is crucial for devices exposed to wear and tear. Both studies underscore the importance of chitosan in enhancing surface durability and scratch resistance. The durability of chitosan coatings under harsh conditions is a critical factor for their practical use and chitosan’s ability to maintain its properties under conditions of abrasion, humidity, and acidity makes it an attractive option for protective coatings. In particular, the findings of Tagliaro et al. (2022) on abrasion resistance and the additional benefits observed CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila in the work by Li et al. (2022) reflect chitosan’s versatility as a coating material for improving the longevity of surfaces. The ability to modify chitosan’s chemical structure to enhance mechanical properties without the need for harmful chemicals or solvents makes it an attractive option for environmentally sustainable surface coatings. As research into chitosan-based coatings progresses, there is a growing recognition of their potential to address not only hydrophobicity and functionality but also to improve the overall mechanical durability of materials. Future developments in surface morphology control and the integration of cross-linking agents could further enhance scratch resistance and long-term durability. Environmental and Sustainable Applications of Chitosan The integration of chitosan in enhancing coating performance has been explored through various innovative approaches, showcasing its potential for creating advanced materials with superior properties. Zhou et al. (2022) developed a method for creating durable, superhydrophobic chitosan-based coatings from waste crab shells by binding chitosan with octadecylamine using glutaraldehyde. These coatings transformed polyurethane sponges into superhydrophobic and superoleophilic absorbents capable of separating organic solvents and oils. Chitosan coatings also demonstrated durability and scratch resistance, making them suitable for protective applications like lens coatings. The study also highlighted the ability of chitosan to form multifunctional coatings that exhibit durability and scratch resistance, crucial for protective applications. This aspect is particularly relevant for developing high-performance coatings, such CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila as those used for lens protection, where the enhancement of durability is essential. However, further research is needed to explore their use in specific areas, such as orthopedic scaffolds, and to optimize preparation methods for improved performance across various applications. Aguilar-Ruiz et al. (2023) studied chitosan-based coatings to prevent aluminum corrosion in seawater. Developed by dissolving chitosan in an acidic solution with additives, these coatings were applied to aluminum substrates and tested using electrochemical methods and immersion in seawater. The results showed effective corrosion protection, with additives like graphene oxide improving barrier properties and resistance. The coatings exhibited strong adhesion, stability, and minimal degradation, outperforming some commercial inhibitors. While eco-friendly and promising as sustainable alternatives, further research is needed to understand their scratch resistance and durability, enhancing their potential in marine applications. Recent advancements in chitosan nanoparticles (CNPs) have focused on efficient synthesis methods like the ionic gelation technique using sodium tripolyphosphate (TPP), as highlighted by Thambiliyagodage et al. (2023). This approach, along with green synthesis methods, enhances CNP properties but faces challenges in scaling up, improving efficiency, and reducing costs. Hi and Vigneswaran (2023) further demonstrated TPP’s role in boosting the thermal stability, strength, and hydrophilicity of CNPs, while exploring alternative cross-linkers like cinnamaldehyde and natural agents such as Pelargonium graveolens. Despite their promise in antimicrobial treatments, dye removal, and medical applications, long-term stability, environmental sustainability, and broader biological interactions require further research. In conclusion, chitosan-based materials demonstrate versatility in applications like CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila antimicrobial treatments, dye removal, drug delivery, tissue engineering, and sustainable corrosion prevention. Innovations such as ionic gelation and green synthesis have improved their mechanical, thermal, and functional properties, with eco-friendly coatings from natural sources like crab shells showing durability and corrosion resistance. Despite their potential, challenges in large-scale production, long-term stability, and environmental impact remain, requiring further research to refine synthesis methods and enhance their sustainability and functionality. Chitosan’s Molecular Interactions and Material Science Chitosan, a biopolymer derived from chitin, is a versatile material with properties like biocompatibility, biodegradability, and the ability to form films and scaffolds. These traits make it suitable for a wide range of applications, including orthopedic implants, wound healing, drug delivery systems, and coatings for both medical and industrial uses. The molecular structure of chitosan, composed of glucosamine and N-acetylglucosamine units, can be modified to enhance its physical, chemical, and biological properties, with key factors such as degree of deacetylation (DD) and molecular weight (MW) playing a role in its adaptability for various applications. The material’s amino groups (-NH2) are highly reactive, allowing chitosan to form bonds with other materials, drugs, and biological molecules. Modifying the molecular structure through techniques like surface functionalization and crosslinking can enhance its mechanical strength, stability, and bioactivity, making it suitable for demanding applications. Alves et al. (2021) explored surface functionalization techniques to improve chitosan's interaction with biological tissues, particularly in orthopedic implants. Their study emphasized how grafting or crosslinking CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila could enhance hydrophilicity and introduce bioactive groups, promoting better cell adhesion and osseointegration for long-term use in orthopedic devices. Pinto et al. (2019) examined the use of glutaraldehyde crosslinking to improve the mechanical strength and stability of chitosan scaffolds for bone tissue engineering. They found that this method not only strengthened the scaffolds but also facilitated the incorporation of bioactive materials like calcium phosphate, enhancing their bioactivity and promoting bone cell growth, which is crucial for osseointegration. Thambiliyagodage et al. (2023) reviewed various synthesis methods for chitosan nanoparticles (CNPs), highlighting the use of crosslinking agents like sodium tripolyphosphate (TPP) and glutaraldehyde to improve the nanoparticles’ mechanical properties, stability, and hydrophilicity. This made CNPs suitable for applications like drug delivery and environmental remediation. Additionally, green synthesis methods, which utilize natural plant extracts, offer a more environmentally sustainable approach compared to traditional chemical crosslinkers, though challenges remain in scaling up these methods for industrial use. Despite these advancements, challenges persist in fully understanding chitosan’s molecular interactions, particularly under varying environmental conditions such as pH, ionic strength, and temperature. The degree of crosslinking plays a significant role in chitosan’s behavior, affecting its degradation rate, bioactivity, and performance in biomedical applications. As Thambiliyagodage et al. (2023) noted, the modification of chitosan’s interactions through crosslinking and surface functionalization can also enhance drug encapsulation and release, improving therapeutic efficacy. However, balancing mechanical strength, biocompatibility, and degradation rate remains a key challenge. CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila Broad Overviews of Chitosan Applications Chitosan has been widely acknowledged owing to the very wide applications of the biopolymer within the industrial sectors. It also has great potential to be used in lens coating applications where scratch resistance, antimicrobial properties, and enhanced durability are achieved. Chitosan's range of potential applications reflects its versatility across a wide range of industries. According to Carmen Jimenez-Gomez et al. (2020), the general perception is that chitosan is a highly biocompatible biopolymer attributed to its biodegradable, adhesive, and bioactive properties, where such a naturally occurring product meets a broad application, especially in the biomedical sector. From biomedical innovations and water treatment to agriculture, chitosan becomes useful because of its unique properties. The advancement creates a potential in creating eco-friendly coatings, particularly in the field of optical applications. Aljibori et al. (2024) give insights into chitosan's chemical compositions, properties, and its application in ophthalmic lenses, as well as in the field of lens technology. Future ophthalmic coatings potential benefits. Chitosan is a biopolymer obtained from the derivative of chitin. It consists of excellent properties, which include bio-compatibility, has antimicrobial activity, and retains moisture. It is one of those materials that is eco-friendly and has facile processing. Carmen Jimenez-Gomez et al. (2020) mentioned using cross-linking agents, like glutaraldehyde, in the preparation of membranes with proton conductivity appropriate for fuel cell applications since the modification in the structure to create it with better properties. CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila Preparation and engineering of chitosan to porous structures or surface area improved result in tremendous enhancements of its functionality for all sorts of applications. Cross-linking of chitosan with agents such as glutaraldehyde is possible as extreme tensile coatings which are optically transparent-a requirement for lenses and other optical surfaces. Ultimately, the outstanding versatility and biodegradable properties of chitosan make it a very promising material over a wide range of applications ranging from biomedical applications to complex optical technologies. These biocompatibility, biodegradability, and antimicrobial properties make it suitable for sustainable high-performance applications, especially within the framework of coatings for ophthalmic lenses. It has been revealed that the cross-linking of chitosan using agents like glutaraldehyde enhances its mechanical strength, adhesion, and scratch resistance to protect optical surfaces for the toughest surfaces. Altogether, they emphasize the versatility and applicability of chitosan as a sustainable substitute in many fields toward the direction of future innovation for sustainable material development. This research provides an integrated overview of the existing knowledge on chitosan-based coatings and adhesives, highlighting its potential, comparative advantages, and the gaps in current understanding. By synthesizing findings from various studies across multiple fields, it offers a comprehensive analysis of how chitosan can be optimized for specialized applications, particularly in the optical industry. Numerous studies have investigated the use of chitosan in various applications, particularly its role in enhancing material properties such as durability, moisture retention, and environmental resistance. Research has shown that chitosan-based coatings can be particularly CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila effective in protecting materials, such as optical lenses and metal substrates, from environmental factors like corrosion and fogging. Additionally, its potential for use in optical devices, including coatings that reduce fogging and inhibit microbial growth, further demonstrates the versatility of chitosan-based materials in high-performance applications. Recent studies highlight chitosan's potential in various fields, significant research gaps remain, particularly in evaluating long-term durability and performance under real-world conditions. This research addresses these gaps by proposing comprehensive environmental testing and tailoring chitosan formulations specifically for ophthalmic lenses. While various methods have been explored to enhance chitosan’s adhesive properties, there is limited research on optimizing its formulations for specific applications, such as ophthalmic lenses. A key gap in the existing literature is the lack of comprehensive studies that assess both the environmental impact and the long-term performance of chitosan-based coatings and adhesives under real-world conditions. This research aims to fill this gap by systematically evaluating the factors that affect the performance, durability, and environmental sustainability of chitosan-based materials, providing insights into their industrial viability. Furthermore, the study explores the mechanisms behind chitosan's adhesive strength and its interactions with other natural polymers, offering a deeper understanding of how these materials can be optimized for specific applications. In conclusion, this research offers a sustainable and high-performance solution for enhancing CR-39 lenses, contributing to advancements in optical technology. Future research should explore large-scale production and long-term environmental impacts to validate these findings further. By addressing both durability and sustainability, this work paves the way for eco-friendly innovations in the optical industry. CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila CHAPTER 3 Methods and Procedures This chapter outlines the methods of research, detailing the techniques employed in conducting the study. It covers the research locale, the sampling technique, the research instrument utilized, and the research protocol followed. Methods of Research The researchers will adopt a quantitative quasi-experimental design that follows research methods referenced from related literature. The use of chitosan powder in developing eco-friendly scratch-resistant coatings for CR-39 ophthalmic lenses while utilizing coating techniques such as dip coating and spin coating. The study has different optimum ratios of formulation which include acetic acid, glycerol, a base biopolymer of chitosan, and glutaraldehyde. Its eco-friendliness will be thoroughly validated by the Department of Environment and Natural Resources (DENR) by conducting Environmental Impact Assessments and Environmental Compliance Certificate. Furthermore, the CR-39 lenses will be divided into two groups of lenses each: Chitosan-Coated Group (coated with a chitosan solution), and Commercial Coating Group (coated with a commercially available scratch-resistant coating). The lenses will be subjected to a standardized scratch-resistance testing, as well as its adhesion, optical clarity, and durability. The degree of scratch resistance will be evaluated using a checklist for the data protocol in coating performance evaluation. Data will be analyzed using ANOVA to compare the mean scratch resistance among the two groups. CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila Research Subjects In this study, the subjects used are CR-39 Ophthalmic Lenses ranging from +3.00 D Sph to -3.00 D sph to equally evaluate the effectiveness of the chitosan-based anti-scratch resistant coatings. Research Locale The research investigation and synthesizing was conducted at Plastilens International Inc. (PII) located at Padre Gomez St, Quiapo, Manila, Philippines. Founded in 1976, this ophthalmic laboratory holds the title of being an established lens laboratory with a long history as one of the pioneers in the industry. Plastilens’ industrial manufacturing plants adhere to quality standards and have ISO certifications for their products, justifying why the laboratory has maintained its reputation as a trusted partner of leading optical clinics and eye care centers in the Philippines. Plastilens is a suitable testing laboratory for this study since they offer scratch resistance testers and optical clarity-measuring devices like Spectrophotometer. Plastilens International Inc. CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila Sampling Technique The researchers concluded which sampling method would best represent the results of the study based on several factors and considerations such as the following: 1. Material composition - Alteration of results happens when there are different material compositions such as existing lens coating and curvature. The researchers decided to use CR-39 lenses without existing coatings to focus on the sole effect of Chitosan’s scratch-resistance. In terms of lens curvature, The researchers opted to use both plus and minus lenses ranging from +3.00D sph to -3.00D sph to obtain an equal basis of comparison between the two types of lenses. 2. Application method - In order to achieve a consistent result, the researchers chose several methods of applying the coating such as dip coating, spray coating, and spin coating. This will also ensure that the coatings are evenly distributed across lenses. 3. Testing conditions - As a way of securing the scratch-resistant mechanism of Chitosan as a coating of CR-39 lens will not be influenced by any external factor that could alter the results of the experiment, the researchers used a testing condition in which the lenses are placed under normal conditions (normal room temperature). With this, the most suitable sampling method for this study would be random systematic sampling, in which the selection of the sample lenses is well-represented across all variants such as lens curvature and lens properties, while also allowing unbiased analysis of the CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila experiment using certain coating application methods, and testing conditions. It also decreases the risk of preferential selection, ensuring that the obtained results are reliable. Research Instrument The following sections outline the criteria used to evaluate the research instruments for assessing the performance of chitosan-based coatings on ophthalmic lenses. It serves as a comprehensive guide for the validation and assessment of key factors such as scratch resistance, optical clarity, abrasion resistance, and adhesion performance. Checklists for the Data Recording Protocol in Coating Performance Evaluation will include: Part I: Evaluation of Coating Durability Under Scratching Conditions It will evaluate the ability of the coating to withstand physical damage like scratching under controlled conditions. This test determines the durability and practical use of ophthalmic lenses coated with chitosan formulation. The key factors measured include the force applied during the test, the depth of the scratch to determine how deeply the scratch penetrates the coating and the visible damage such as scratches or cracks. The severity of the damage is graded, and scratch recovery is observed to see if the coating self-heals after being scratched. A comparative assessment is made between the scratch visibility before and after the test, providing insights into the coating’s performance. The overall scratch resistance of the coating is then evaluated to determine its sustainability for every use in ophthalmic applications Part II: Assessment of Optical Transparency and Clarity of Coated Lenses CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila This test evaluates the transparency and visual quality of a material by examining various factors. These include the test method used, the percentage of light transmitted through the material, and the surface smoothness, which is categorized as either smooth or uneven. The presence of haze or distortion is evaluated on a scale, providing insight into any visual cloudiness. Optical performance is also measured by determining the clarity and sharpness of images seen through the material and the compliance with established optical standards, such as ISO and ANSI which ensures that the material meets the required benchmarks for quality and performance. Part III: Evaluation of Coating Durability Under Abrasive Wear This test measures the resilience of the coating to wear and tear, particularly when exposed to abrasive forces during daily use. It measures key factors such as the number of cycles before the coating starts to fail, and the abrasion type used like sandpaper or cloth. The visible surface wear is recorded, along with the changes in surface roughness before and after the test to evaluate the extent of the damage. Additionally, adhesion loss is monitored whether the coating remains securely bonded to the lens during abrasion, and the overall abrasion resistance of the coating is evaluated, providing a clear indication of its durability in several conditions. Part IV: Assessment of Coating Adhesion Strength and Stability The adhesion test evaluates the durability and effectiveness of a coating applied to a lens by assessing several critical factors. These include the bond strength to quantify the adhesion between the coating and the lens. The test also examines adhesion after mechanical or thermal stress, environmental exposure (e.g., humidity, temperature), and the presence of CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila peeling, lifting, or cohesive failure within the coating layer. Proper surface preparation, including cleaning and priming, is verified, as well as the consistency of the applied coating across the lens. A visual inspection checks for any coating detachment or defects. Based on the results of these assessments, the overall adhesion performance is determined as either good or poor, ensuring the coating meets required durability and reliability standards. Data regarding scratch resistance, optical transparency, and surface roughness will be meticulously recorded and compiled for statistical analysis through tables and checklists. The table for the measurement and details in every formulation will include: Part I: Key Parameters for Chitosan-Based Coating Preparation The material properties for preparing chitosan-based coatings are defined by several key parameters. Chitosan concentration is typically measured in grams per liter, determining the primary polymer content. Acetic acid concentration, recorded as a percentage or molarity, serves as a solvent and influences the solubility of chitosan. The crosslinking agent, specified by its type and amount (in milliliters or grams), plays a critical role in enhancing the structural integrity and stability of the coating. Additionally, silica nanoparticles, included for improved mechanical and optical properties, are characterized by their concentration and amount, measured in milligrams, grams, or percentage. These input details are crucial for optimizing the formulation to achieve the desired durability, clarity, and performance of the coating. Part II: Detailed Steps for Sample Preparation and Application The sample preparation process involves several critical steps to ensure consistency and effectiveness in coating application. The solution preparation method specifies the stirring CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila speed, stirring time, and temperature, which are essential for properly dissolving and mixing the components. Following this, the coating application process is defined, detailing the specific technique used to apply the coating onto the material. Finally, the drying/curing conditions are outlined, including the method, temperature, and duration required to properly set the coating. These parameters are carefully controlled to achieve the desired properties and performance of the final coated product. Part III: Comprehensive Testing Data for Coating Evaluation The testing data includes several key tests to evaluate the performance and durability of the coating. The scratch resistance test records the force applied during the test, any observations of damage or changes in the material, and the specific test method used. For the optical clarity test, the percentage of light transmission is noted, along with any presence of haze or distortion, and additional observations about the material's visual quality. The abrasion resistance test tracks the number of cycles before significant wear occurs, measures surface roughness changes, and assesses the percentage of degradation, indicating the coating's resilience to wear. Finally, the adhesion test focuses on any observations regarding the coating's adherence to the lens or material, providing insights into its durability under different conditions. These tests offer a comprehensive analysis of the coating's properties, ensuring its suitability for practical use. Part IV: Evaluation of Surface Roughness for Coating Performance Surface characterization, specifically the measurement of surface roughness, is essential for understanding the texture of a material. Ra (average roughness) and Rz (average maximum height of the surface profile) are common parameters used to quantify surface CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila texture, typically expressed in micrometers or nanometers. These measurements provide insight into how smooth or rough the surface is, which can significantly affect the performance of coatings, particularly in terms of adhesion, durability, and optical properties. A smoother surface often enhances coating adhesion and longevity, while a rougher surface may lead to uneven coverage or weaker bonds. Part V: Impact of Temperature and Humidity on Material Testing Environmental conditions, specifically temperature and humidity, play a crucial role in determining the performance of materials and coatings under test conditions. Temperature, measured in °C or °F, can influence the flexibility, adhesion, and stability of a coating, as well as its ability to withstand thermal stresses. Humidity, expressed as a percentage of relative humidity, is another critical factor that affects the material’s resistance to environmental factors such as corrosion, degradation, or swelling. By controlling and monitoring these conditions during testing, it ensures that the material's behavior is evaluated accurately, simulating real-world usage scenarios where temperature and humidity fluctuations can impact the material's overall performance and durability. Part VI: Documentation of Notes and Observations During Testing The notes/observations section captures important details and findings during the testing process that may not be explicitly measured but are crucial for interpreting results. These observations can include any unusual behaviors, anomalies, or visual cues, such as unexpected changes in texture, color, or performance, that arise during tests. Recording such details helps to contextualize the data, identify potential issues, or highlight specific trends that may require further investigation. This qualitative information complements the quantitative results, providing CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila a fuller understanding of how the material or coating behaves under different conditions, contributing to more accurate assessments and future improvements. Research Protocol The step-by-step process of the data collection procedures of this research are presented in Figure 1: Figure 1: Schematic Diagram of Methodology CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila Stage 1: Ethical Clearance The study will strictly adhere to ethical research standards to ensure integrity and responsibility throughout the process. Permission to the head of CEU Laboratory will be requested to confirm the procedures are conducted in an authorized setting. In line with this, chemical wastes will be disposed of and handled properly to practice safety procedures and prevent incidents. Meanwhile, Chitosan and chemicals will be handled subject to the approval of the Institutional Ethics Review Committee. Since the research study does not involve human and animal subjects, concerns about participant welfare and ethical treatment will not be an issue. Stage 2: Materials and Sample Preparations All the required materials and equipment will be acquired and tested for accuracy, including instruments like the spectrophotometer and hardness tester. Experimental samples shall be prepared by casting CR-39 ophthalmic lenses in solutions with different concentration levels of materials. Consistent application of the methods to each sample shall ensure that the conditions during curing are controlled so that the outcome of the coating is uniform. Stage 3: Organizing Experimental Groups 1. A baseline formulation having moderate chitosan concentration, standard glycerol, and glutaraldehyde. Silica nanoparticles, with a small content, are included to get scratch resistance and clarity. CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila Formula 1: chitosan 1% acetic acid 2% glycerol 10% glutaraldehyde 1% silica nanoparticles 0.1 g 2. Enhanced formulation with higher chitosan and silica nanoparticle content, optimizing scratch resistance and structural integrity while maintaining clarity. Formula 2: chitosan 4% acetic acid 2% glycerol 8% glutaraldehyde 1.5% silica nanoparticles 0.4 g 3. Advanced formulation combining chitosan, increased silica nanoparticle concentration, and titanium dioxide for superior scratch resistance, reduced abrasion, and optimum optical clarity. Formula 3: chitosan 3% acetic acid 2% glycerol 6% glutaraldehyde 1.2% silica nanoparticles 0.5 g titanium dioxide nanoparticles 0.2 g Stage 4: Testing and Characterization 1. Scratch Resistance Test - The coated lenses undergo standardized procedures in the optical labs selected for scratch resistance tests. 2. Adhesion Test - The coated lenses will be subjected to standard operating procedures in the optical labs to evaluate their adhesion. 3. Optical Clarity Test - The coated lenses will undergo rigorous testing to ensure compliance with optical performance standards including assurance of lens clarity. CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila 4. Abrasion Resistance Test - The coated lenses will undergo abrasion cycles, which will evaluate their resistance. Stage 5: Data Recording Data regarding scratch resistance, optical transparency, and surface roughness will be meticulously recorded and compiled for statistical analysis through tables with a subgroup of material property, sample preparation details, testing data, surface characterization, environment conditions, and other notes and observation. The table details and inputs will be described in the following: Material Property The Formulation process includes detailed recording of material inputs and preparation methods. Chitosan concentration is measured in grams per litter, while the acetic acid concentration is expressed as a percentage or molarity, the crosslinking agent involves its type and amount is recorded in millimeters or grams and along with the silica nanoparticles concentration and amount are noted in milligrams, grams or percentage are meticulously recorded. Sample Preparation Details With regard to sample preparation, the solution preparation method details stirring speeds, stirring time and temperature at which the solution is processed. The coating application process is outlined, followed by the input of drying or curing conditions, including the method used, the temperature, and the duration of coating. Given these details will ensure consistency and repeatability in sample preparation. CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila Testing Data For evaluation of scratch resistance testing, note the force applied, test method and scratch resistance observation. Optical clarity measurements include transmission percentage, distortion or haze levels, and overall observations. Abrasion resistance tests record the number of cycles, changes in surface roughness, and degradation percentage, while adhesion tests assess observations on coating performance. This input ensures thorough documentation and analysis of each formulation’s performance. Surface Characterization and Environmental Conditions Surface roughness is measured as part of surface characterization, and parameters such as Ra and Rz are expressed in micrometers or nanometers. During testing, the environmental conditions are documented including temperature (in °C or °F) and humidity in relative percentage. These factors offer essential context for understanding the material’s performance under specific conditions. Notes and observation An essential component of the evaluation is note and observation, any deviations, peculiarities, or notable results observed during testing are recorded systematically, these include visible surface changes, irregularities in performance, or anomalies in material behavior. The observations work all together to provide a thorough examination of the formulation’s characteristics and practicality. CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila The data recording for scratch resistance, optical transparency, and abrasion resistance of coated lenses will be presented here. It addresses the main parameters influencing coating durability such as scratch test force, light intensity in clarity measurements, and wear distribution during the abrasion test. The checklists for the Data Recording Protocol in Coating Performance Evaluation will include: 1. Scratch Resistance Test This checklist involves evaluating the durability of coating under applied force. The force applied during the test will be recorded as measured force in grams or newtons, while depth of scratch is taken note in micrometers or millimeters. The presence of visible scratches or cracks and any recovery or self-healing ability of the coating will be logged. A competitive assessment of pre- and post-test scratch visibility helps quantify resistance through visibility change percentages. Through the overall resistance of the coating is graded as good or poor based on the performance. 2. Optical Clarity Test The optical clarity test evaluates the coating light transmissibility and surface smoothness. The evaluation begins by confirming the method used is under standard optical clarity test method, such as ISO and ASTM. Light transmission is measured as a percentage indicating how much light passes through the coated lens. The presence of haze or distortion is rated on the scale of 1 to 5. Surface smoothness and clarity is assessed by determining the sharpness of an image and ensuring compliance with optical standards. CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila 3. Abrasion Resistance Test The abrasion resistance measures the durability of the coating under abrasive conditions. The checklist involves tracking the number of abrasion cycles before coating failure, the type of abrasive material used such as sand paper or cloth, the visible wear after test, classified as minor, moderate, or severe. Wear is quantified by measuring changes in surface roughness are measured pre- and post-test. Adhesion loss, such as peeling or detachment of the coating is noted and the overall resistance to abrasion is evaluated as good or poor. 4. Adhesion Performance Test This checklist evaluation focuses on the coating’s bond strength and resistance to various stresses. Bond strength is measured as newton or psi. Observations in regards to peeling or lifting of the coating under mechanical, thermal or environmental stresses like humidity and temperature changes are also recorded. The cohesive failure within the coating layer or priming will be also documented. Consistency of the applied coating across the lens, along with visual inspection for detachment or defects, forms the basis for final assessment as good or poor adhesion performance. Stage 6: Data Analysis Statistical methods will be applied for data analysis, employing ANOVA to obtain a difference between the experimental groups with different formulations and those in the control group, which contains a conventional anti-scratch lens coating. It will help observe any performance metrics such as adhesion strength, scratch resistance, optical clarity, and abrasion CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila resistance across all the experimental groups. On statistical grounds, by use of ANOVA, the study will determine if any differences are statistically significant to confirm the efficacy of chitosan as an alternative adhesive binder for scratch-resistant coatings. These data-driven results will then be used to choose the best formula that obtains the most effective coating. Stage 7: Data Interpretation The results obtained from different tests that have been performed on experimental samples will be interpreted. The ideal concentration of chitosan for desirable properties will be selected based on the criteria from the data recordings. Finally, the best-performing formula that balances performance metrics with practicality will be selected. These will be compared against existing benchmarks for conventional scratch-resistant coatings to determine the effectiveness of chitosan as an alternative binder. The data interpretation will be guided by the statistical outcomes, to ensure a complete and objective analysis of the results of this study. Validation of Instruments and Procedures All instruments will be calibrated before the study begins, and preliminary trials will be conducted to validate the methods and ensure consistency and reliability of results Validation Form Innovative Use of Chitosan Powder in Developing Eco-Friendly Scratch-Resistant Coatings for CR-39 Ophthalmic Lens Section 1: Validator Information Name:________________________________________________________________ Position/Title:___________________________________________________________ CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila Institution/Organization:___________________________________________________ Field of Expertise:________________________________________________________ Contact Information:______________________________________________________ Section 2: Instrument Assessment Kindly evaluate the research instruments based on the following criteria. Place a checkmark (✓) in the appropriate column and provide comments or suggestions if applicable. Criteria Excellent Good Fair Poor Comments/ Suggestions Clarity and Understandability Relevance to the Research Goals Adequacy of Content Appropriateness of Materials Feasibility of Implementation Alignment with Ethical Standards Section 3: Specific Instrument Feedback 1. Preparation of Coating Solutions Are the steps and materials clearly defined? ☐ Yes ☐ No CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila Comments: ____________________________________________________________ 2. Coating Application Process Is the procedure practical and achievable with the specified materials and equipment? ☐ Yes ☐ No Comments: ____________________________________________________________ 3. Testing and Characterization Methods Are the proposed tests (e.g., scratch resistance, optical clarity) suitable for evaluating coating performance? ☐ Yes ☐ No Comments: ____________________________________________________________ 4. Data Collection and Analysis Do the proposed methods for collecting and analyzing data align with the study objectives? ☐ Yes ☐ No Comments: ____________________________________________________________ Section 4: Recommendations Please provide any recommendations to improve the instruments or overall research framework. Section 5: Validator’s Approval Based on your evaluation, do you approve the use of these research instruments for this study? ☐ Yes ☐ No Validator's Signature: _____________________________ Date: _____________________ This form ensures that the research instruments undergo expert review, enhancing their reliability and alignment with the study's objectives. CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila Data Recording Protocol in Coating Performance Evaluation Checklists The data recording for scratch resistance, optical transparency, and abrasion resistance of coated lenses will be presented here. It addresses the main parameters influencing coating durability such as scratch test force, light intensity in clarity measurements, and wear distribution during the abrasion test. Checklists for the Data Recording Protocol in Coating Performance Evaluation includes: Scratch Resistance Test Factor Criteria Data to Record Test Method Used Standard Test Method Yes / No Applied (e.g., ASTM, ISO) Force Applied Force applied during the Measured Force (N) test (grams, Newtons) Scratch Depth Depth of scratch Scratch Depth (µm or mm) (micrometers, millimeters) Visible Damage Presence of visible Yes / No scratches or cracks Severity of Scratch Severity (minor, moderate, Severity (1–3 scale) severe) Scratch Recovery Pre- vs. Post-test scratch Yes / No visibility comparison Comparative Pre- vs. Post-test scratch Scratch Visibility Change Assessment visibility comparison (%) Overall Scratch Good or poor scratch Yes / No Resistance resistance CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila Optical Clarity Test Factor Criteria Data to Record Test Method Used Standard optical clarity test Yes / No (e.g., light transmission percentage) Transmission Light transmission (% of Transmission Percentage Percentage light passed through) (%) Surface Smoothness Surface smoothness Yes / No (smooth or uneven texture) Haze or Distortion Presence of haze or Haze Level distortion (Scale 1–5) Optical Performance Clarity and sharpness of Clarity Rating image (1–5 scale) Standards Compliance Meets optical clarity Yes / No standards (ISO, ANSI) Abrasion Resistance Test Factor Criteria Data to Record Test Method Used Standard abrasion Yes / No resistance test (e.g., number of cycles) Number of Cycles Number of abrasion cycles Number of Cycles before coating failure Abrasion Type Type of abrasive material Abrasive Type used (e.g., sandpaper, cloth) Visible Surface Wear Visible wear after test Wear Severity (1–3 scale) (minor, severe) CENTRO ESCOLAR UNIVERSITY SCHOOL OF OPTOMETRY Mendiola, Metro Manila Surface Roughness Change in surface Surface Roughness (µm) Change roughness (pre- vs. post-test) Adhesion Loss Loss of adhesion or Yes / No coating peeling Overall Abrasion Good or poor abrasion Yes / No Resistance resistance Adhesion Performance Test Factor Criteria Data to Record Test Method Used Standard abrasion Yes / No resistance test (e.g., number of cycles) Bond Strength Measure of bond strength Bond Strength (N or psi) between coating and lens Adhesion After Stress Adhesion after mechanical Yes / No or thermal stress Adhesion After Exposure Adhesion after Yes / No environmental exposure (e.g., humidity, temperature) Peeling or Lifting Presence of peeling or Yes / No lifting of

Innovative Chitosan Coatings for CR-39 Lenses - Centro Escolar University

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