Unit 4 Part B Biopolymers PDF

Course title: Environmental Science and Green Chemistry Course Code: FCCH0103 Chapter: 4 Green Fuels and Bio-Polymer chemistry: Part:B Synthesis and applications of certain: biocompatible polymers - Polylactic Acid, Cellulose and Polyvinyl alcohol (PVA)...

Course title: Environmental Science and Green Chemistry Course Code: FCCH0103 Chapter: 4 Green Fuels and Bio-Polymer chemistry: Part:B Synthesis and applications of certain: biocompatible polymers - Polylactic Acid, Cellulose and Polyvinyl alcohol (PVA), Nanomaterials; Advantages of biocompatible materials over synthetic materials. 1 Lessons from First-Generation Biofuels: ✓ Sustainability is based in economic, social, and environmental aspects. ✓ When all three criteria are met, sustainable development is possible ✓ As shown below, in theory both economic, social, and environmental aspects has been considered ✓ However current state the economic aspect is focused more and environmental in not even valued much. ✓ Where as, the change is needed to balance all so that environment can be protected for the sustainable development The Theory Now The Change needed DOI: 10.1007/978-3-319-14409-2_91 2  Introduction: Biodegradable polymers Why are biodegradable polymers important? In groups of 2-3, you have two minutes to come up with answers! Environmental factors (avoidance of persistent plastics) “Smart” applications e.g. drug delivery devices, agricultural use 3  Introduction: Biodegradable polymers These polymers are derived from biobased material/resources. The Biodegradable polymers undergoes the process of biodegradation Phenomenon of Biodegradation is the degradation of a material by environmental factors such as sunlight, temperature changes or the action of microbes. In polymer science and engineering, the design of polymers susceptible to biodegradation is of increasing importance for two reasons a) polymers that degrade naturally in the body to harmless products may be used in biological devices and in drug delivery, and b) polymers that break down in the environment are significantly ‘greener’ than traditional plastics DOI: 10.1007/978-3-319-14409-2_91 4  Biodegradable and nonbiodegradable bioplastics As shown in the figure, ✓ Biodegradable polymers can be made from renewable raw material, Ex: PLA, PHA, Starch ✓ Biopolymers which are not biodegradable can also be obtained from renewable raw material, Ex: Bio-PE, PET. ✓ On the other hand, petrochemical raw material also contributes in the development of conventional polymers like PE, PP, PET which are not biodegradable, ✓ however the few biopolymers can also obtained using petrochemical raw material DOI: 10.1007/978-3-319-14409-2_91 5 We will study and discuss the synthesis and applications of following biodegradable polymers: Polylactic Acid Polyvinyl alcohol (PVA) 6  Polylactic acid (PLA) PLA is derived from the Lactic acid(2-hydroxypropionic acid, CH3CHOHCOOH). A naturally occurring organic acid (existing in two enantiomeric forms, L- and D-LA) 7  Synthesis ▪PLA synthesis starts from the production of LA (lactic acid) and ends with its polymerization with an intermediate step of lactide formation. ▪PLAs are basically synthesized in three steps, (i) LA production by microbial fermentation, (ii) LA purification followed by its cyclic dimer (lactide) preparation and (iii) polycondensation of LA or ring-opening polymerization (ROP) of lactides ▪Condensation polymerization (polycondensation) includes solution polycondensation and melt polycondensation and is the least expensive route. ▪Enzymatic polymerization is emerging as one of the most viable alternatives and is an environmentally benign method that can be carried out under mild conditions 8  Synthesis: Schematic representation As shown in the scheme, L-LA or D-LA can be used for the synthesis of PLA by direct condensation polymerization results in low molecular weight PLA which further reaction with chain coupling agent gives high molecular weight polymer, Similarly, polymerization through lactide formation followed by ring opening polymerization results in the high molecular weight PLA. However Azeotropic dehydration condensation gives direct High Mol. Wt. PLA https://www.google.com/search?sca_esv=556766949&rlz=1C1ONGR_enIN1050IN1050&q=polylactic+acid&tbm=isch&source=lnms&sa=X&ved=2ahUKEwjM- d6dtNyAAxUqpukKHaVIA9UQ0pQJegQIDRAB&biw=1536&bih=739&dpr=1.25#imgrc=zc53-sqHzoK_MM&imgdii=daGjE8FN16HBXM 9  Properties of PLA ✓ PLA has high mechanical properties and excellent shaping and molding properties. ✓ PLA is a biodegradable, bioabsorbable, pseudoplastic, and renewable thermoplastic polymer ✓ It is biocompatible (which means it has good blood and tissue compatibility, and if slow degradation takes place, the degradation products are non-toxic) ✓ It is bioresorbable (which means it can be broken down by the body and does not require mechanical removal) in the human body. ✓ High molecular weight polymer material is necessary for applications such as bone plates or temporary internal fixation of broken or damaged bones ✓ PLA has favourable physical properties such as transparency, high elastic modulus and high melting temperature which often improves function as well as diminish environmental impact ✓ This polymer is a good candidate for sheet extrusion, film blowing, as well as fiber spinning https://doi.org/10.1002/pen.26193 10  Application PLA has been widely studied for use in medical applications because of its bioresorbable and biocompatible properties in the human body. The diversification of PLA applications is such that a single polymer may prove useful in many applications by simple modifications of its physical– chemical structure Further, PLA can be recycled into lactic acid 11  Polyvinyl alcohol (Introduction) It is produced commercially from polyvinyl acetate, usually by a continuous process Polyvinyl alcohol is an odorless and tasteless, translucent, white or cream-colored granular powder It is soluble in water, slightly soluble in ethanol, but insoluble in other organic solvents. PVA is an artificial polymer that has been used during the first half of the 20th century worldwide 12  Synthesis Polyvinyl alcohol PVA is not made by polymerizing the corresponding monomer, vinyl alcohol, because it is thermodynamically unstable and tautomerized to acetaldehyde. PVA is made by hydrolyzing polyvinyl acetate or other vinyl ester-derived polymers with formate or chloroacetate groups instead of acetate. The polyvinyl esters are typically converted via base-catalyzed transesterification with ethanol Synthetic scheme 13  Properties Polyvinyl alcohol has high flexibility and tensile strength. Polyvinyl alcohol is miscible in water due to presence of hydroxyl group. Its molecular weight ranges from about 26,000 to 30,000 g mol-1. Polyvinyl alcohol is immiscible in organic solvents except for slightly soluble ethanol. Polyvinyl alcohol is ductile but also strong and flexible. It also functions as an aroma and high oxygen barrier. 14  Application Textile Industry: PVA is used in sizing agents to improve the weaving process of yarn, providing increased strength and reduced friction Paper Industry: PVA is employed as a surface sizing agent to improve paper's surface strength, printability, and ink absorption. Adhesives: PVA-based adhesives are widely used in woodworking, packaging, and bookbinding due to their strong adhesive properties, ease of use, and low toxicity. Food Packaging: PVA films are used as food packaging materials due to their excellent barrier properties against gases and oils. They can also be used as edible coatings to extend the shelf life of fruits and vegetables. Pharmaceuticals: PVA is used in the pharmaceutical industry to make controlled-release drug formulations, capsules, and tablets. https://en.wikipedia.org/wiki/Polyvinyl_alcohol 15  Reference: 1. Poly(Lactic Acid)-Based Biomaterials: Synthesis, Modification and Applications, Biomedical Science, Engineering and Technology , www.intechopen.com 2. Synthesis, properties, and applications of polylactic acid-based polymers https://doi.org/10.1002/pen.26193 3. Synthesis of polylactic acid for biomedical, food packaging and structural applications: A review https://www.researchgate.net/publication/261672499 4. Polyvinyl Alcohol: A Review of Research Status and Use of Polyvinyl Alcohol Based Nanocomposites, POLYMER ENGINEERING AND SCIENCE—2018, DOI 10.1002/pen 5. Polyvinyl alcohol: A review of research status and use of polyvinyl alcohol based nanocomposites, https://doi.org/10.1002/pen.24855 6. https://www.sekisui-sc.com/products/polyvinyl-alcohol/ 7. Recent Advances: Green Biopolymer Nanocomposites, Springer-Nature, Singapore, Chapter_10_3rd_Revision_5.docx (287.16K) 16