Podcast
Questions and Answers
What is the primary reason for the attention on bio-based hydrogels derived from natural resources?
What is the primary reason for the attention on bio-based hydrogels derived from natural resources?
- They are easily accessible.
- They are cost-effective.
- They have a higher yield than synthetic alternatives.
- They have high biodegradability and biocompatibility. (correct)
Which property of cellulose makes it suitable for hydrogel formation?
Which property of cellulose makes it suitable for hydrogel formation?
- High melting point.
- High lignin content.
- Low crystal structure.
- Abundant reactive hydroxyl groups. (correct)
What solvent mixture is used to dissolve cellulose from water hyacinth in this study?
What solvent mixture is used to dissolve cellulose from water hyacinth in this study?
- Methanol/chloroform.
- NaOH/urea. (correct)
- Acetic acid/acetone.
- Ethanol/water.
Which method of cross-linking is selected for preparing cellulose hydrogels due to its stability?
Which method of cross-linking is selected for preparing cellulose hydrogels due to its stability?
What is the purpose of the Segal's empirical method in determining the crystallinity index?
What is the purpose of the Segal's empirical method in determining the crystallinity index?
At what temperature range was the thermogravimetric analysis (TGA) conducted?
At what temperature range was the thermogravimetric analysis (TGA) conducted?
What environmental problem is caused by water hyacinth?
What environmental problem is caused by water hyacinth?
What is the average lignin content in water hyacinth, making it suitable for cellulose extraction?
What is the average lignin content in water hyacinth, making it suitable for cellulose extraction?
What is the main function of sputter coating the hydrogel sample before SEM analysis?
What is the main function of sputter coating the hydrogel sample before SEM analysis?
What is the main drawback of physical cross-linking compared to chemical cross-linking?
What is the main drawback of physical cross-linking compared to chemical cross-linking?
What component is specifically analyzed using UV–Vis spectroscopy?
What component is specifically analyzed using UV–Vis spectroscopy?
Which peak intensity is associated with the amorphous part of the material in the crystallinity index formula?
Which peak intensity is associated with the amorphous part of the material in the crystallinity index formula?
Why is the cellulose extracted from water hyacinth considered an alternative material?
Why is the cellulose extracted from water hyacinth considered an alternative material?
What is the significance of measuring the swelling ratio in cross-linked cellulose-based hydrogels?
What is the significance of measuring the swelling ratio in cross-linked cellulose-based hydrogels?
What effect does the flow rate of nitrogen have during the TGA process?
What effect does the flow rate of nitrogen have during the TGA process?
What was the scanning speed employed during the UV–Vis spectroscopy measurements?
What was the scanning speed employed during the UV–Vis spectroscopy measurements?
What was the transparency percentage of the uncross-linked hydrogel at 600 nm?
What was the transparency percentage of the uncross-linked hydrogel at 600 nm?
How did the transparency of the cross-linked B5 hydrogel compare to that of the uncross-linked B0 hydrogel?
How did the transparency of the cross-linked B5 hydrogel compare to that of the uncross-linked B0 hydrogel?
What likely caused the decrease in transparency of the cross-linked hydrogels with increased borax?
What likely caused the decrease in transparency of the cross-linked hydrogels with increased borax?
What structural feature was observed in the uncross-linked cellulose hydrogel?
What structural feature was observed in the uncross-linked cellulose hydrogel?
What was the pore diameter of the B1 hydrogel observed in the study?
What was the pore diameter of the B1 hydrogel observed in the study?
What type of structure did the addition of borax create in the cellulose hydrogel?
What type of structure did the addition of borax create in the cellulose hydrogel?
Which other additive was mentioned as affecting transparency in hydrogels in a similar manner to borax?
Which other additive was mentioned as affecting transparency in hydrogels in a similar manner to borax?
What is the main bonding mechanism responsible for the structure of the uncross-linked cellulose hydrogel?
What is the main bonding mechanism responsible for the structure of the uncross-linked cellulose hydrogel?
What is the primary cellulose source discussed in the studies?
What is the primary cellulose source discussed in the studies?
Which method is noted for extracting nanofibrillated cellulose from water hyacinth?
Which method is noted for extracting nanofibrillated cellulose from water hyacinth?
What characteristic of cellulose obtained from water hyacinth is emphasized in its applications?
What characteristic of cellulose obtained from water hyacinth is emphasized in its applications?
Which publication discusses the synthesis and characterization of dissolved cellulose for benzylation?
Which publication discusses the synthesis and characterization of dissolved cellulose for benzylation?
What type of hydrogels are derived from carboxymethyl cellulose and polyaniline?
What type of hydrogels are derived from carboxymethyl cellulose and polyaniline?
Which crosslinking agent is identified as nontoxic in the preparation of hydrogels?
Which crosslinking agent is identified as nontoxic in the preparation of hydrogels?
In which year was the study on advances in crosslinking strategies of biomedical hydrogels published?
In which year was the study on advances in crosslinking strategies of biomedical hydrogels published?
What is a notable feature of cellulose nanofibers extracted from water hyacinth?
What is a notable feature of cellulose nanofibers extracted from water hyacinth?
What do cellulose nanocrystals (CNC) reinforce in the study by Geng et al. (2016)?
What do cellulose nanocrystals (CNC) reinforce in the study by Geng et al. (2016)?
Which property is NOT associated with the PVA-borax hydrogels developed by Lu et al. (2017)?
Which property is NOT associated with the PVA-borax hydrogels developed by Lu et al. (2017)?
What characterizes the all-cellulose composites mentioned in the study by Duchemin et al. (2016)?
What characterizes the all-cellulose composites mentioned in the study by Duchemin et al. (2016)?
Which analytical method did Segal et al. (1959) propose for estimating crystallinity in cellulose?
Which analytical method did Segal et al. (1959) propose for estimating crystallinity in cellulose?
What was the focus of the research conducted by Tang et al. (2019)?
What was the focus of the research conducted by Tang et al. (2019)?
What did Wei et al. (2020) control to influence the properties of all-cellulose composites?
What did Wei et al. (2020) control to influence the properties of all-cellulose composites?
Which year was the study by Lin et al. (2000) on poly(vinyl alcohol)-borax semidilute solutions published?
Which year was the study by Lin et al. (2000) on poly(vinyl alcohol)-borax semidilute solutions published?
Which application is mentioned in relation to microfibrillated cellulose in the studies provided?
Which application is mentioned in relation to microfibrillated cellulose in the studies provided?
What happens to Tmax of cross-linked cellulose materials as borax concentration increases?
What happens to Tmax of cross-linked cellulose materials as borax concentration increases?
What was the Tmax value of B5 hydrogels?
What was the Tmax value of B5 hydrogels?
What is a probable cause for the decrease in thermal stability of the hydrogels with more borax?
What is a probable cause for the decrease in thermal stability of the hydrogels with more borax?
What trend was observed regarding the DTG peak height with the introduction of borax?
What trend was observed regarding the DTG peak height with the introduction of borax?
How did the total char formed at 700 °C change with varying borax concentrations?
How did the total char formed at 700 °C change with varying borax concentrations?
What was the fire growth rate of the B5 sample?
What was the fire growth rate of the B5 sample?
What trend was observed in fire growth rates as borax concentrations increased?
What trend was observed in fire growth rates as borax concentrations increased?
What is suggested to have contributed to delaying flame ignition and propagation?
What is suggested to have contributed to delaying flame ignition and propagation?
Flashcards
Bio-based hydrogels
Bio-based hydrogels
A type of material made from natural resources like cellulose, commonly used for its biodegradability, biocompatibility, and environmental sustainability.
Cellulose
Cellulose
A polysaccharide found in plants, particularly abundant in water hyacinth, exhibiting a strong, fibrous structure due to numerous hydroxyl groups.
Water hyacinth (Eichhornia crassipes)
Water hyacinth (Eichhornia crassipes)
A common aquatic weed known for rapid growth, blocking waterways and negatively impacting aquatic life.
Cross-linking
Cross-linking
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Chemical cross-linking
Chemical cross-linking
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NaOH/urea solution
NaOH/urea solution
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Water absorbency
Water absorbency
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Crystalline domains
Crystalline domains
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Crystallinity Index
Crystallinity Index
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Tmax
Tmax
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Esterification of Cellulose
Esterification of Cellulose
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Thermogravimetric Analysis (TGA)
Thermogravimetric Analysis (TGA)
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Fire Growth Rate
Fire Growth Rate
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UV-Vis Spectroscopy
UV-Vis Spectroscopy
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Scanning Electron Microscopy (SEM)
Scanning Electron Microscopy (SEM)
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Thermal Annealing
Thermal Annealing
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Total Char
Total Char
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Water Content/Swelling Ratio
Water Content/Swelling Ratio
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Fire Retardancy
Fire Retardancy
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Gel Fraction
Gel Fraction
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Transparency
Transparency
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Borax Incorporation
Borax Incorporation
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Freeze-drying
Freeze-drying
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Porous structure
Porous structure
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Pores
Pores
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Morphology
Morphology
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Defibrillation
Defibrillation
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Hydrogel
Hydrogel
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Study Notes
Superabsorbent Cellulose-Based Hydrogels Cross-Linked with Borax
- Cellulose, a prevalent biopolymer, is desirable due to its availability, biodegradability, and non-toxicity.
- Environmentally friendly hydrogels were created from water hyacinth cellulose using a sodium hydroxide and urea dissolution approach, cross-linked with borax (sodium tetraborate decahydrate).
- The uncrosslinked hydrogels exhibited a swelling ratio of 325%, while the crosslinked hydrogels reached approximately 900%.
- Increasing borax concentration boosted the gel fraction in the crosslinked hydrogels.
- Borax formed a char on the cellulose surface, creating a delay in flame ignition and propagation.
- The crosslinked hydrogels displayed antimicrobial activity against gram-positive bacteria (Staphylococcus aureus).
- Potential applications include wound dressings, agricultural uses, and flame-retardant coatings.
Hydrogel Properties and Preparation
- Hydrogels are three-dimensional, crosslinked networks of hydrophilic polymers capable of absorbing and retaining significant amounts of water without dissolving.
- Bio-based hydrogels, derived from natural sources (like cellulose, hyaluronate, and alginate), are gaining interest due to their biocompatibility, biodegradability, and sustainability.
- Cellulose excels due to high yield, abundance, and natural replenishment from plants.
- Water hyacinth, an abundant aquatic weed, offers an alternative source for cellulose extraction due to its porous structure and low lignin content.
- Cellulose dissolution, a prerequisite for hydrogel formation, requires a specific solvent or condition to overcome strong intra- and inter-molecular hydrogen bonds in its crystalline structure.
- NaOH/urea solution was utilized for dissolving water hyacinth-extracted cellulose in the study due to its low toxicity, rapid dissolution, and cost-effectiveness.
- Chemical cross-linking with low-toxicity agents is preferred to form the hydrogel structure. Borax is a suitable option due to its low toxicity, low cost, and water solubility.
Experimental Methods
- Water hyacinth fibers were obtained and refined through dewaxing, alkaline treatment, bleaching, and acid hydrolysis.
- The crosslinked cellulose-based hydrogels were prepared by dissolving treated cellulose fibers in a NaOH/urea solution and combining with various borax concentrations.
- Characterization included FTIR spectroscopy for functional group analysis, XRD for crystallinity analysis, TGA for thermal stability assessment, UV-Vis spectroscopy for optical transmittance, and SEM for morphological examination.
- Water content, swelling ratio, and gel fraction were quantitatively measured to evaluate water absorption capacity.
- An antibacterial activity test using AATCC 100 standard was applied to examine the efficacy against E. coli and S. aureus.
Results and Discussion
- Chemical changes were observed via FTIR analysis, showing the shift in characteristic peaks of cellulose and the appearance of borax-specific peaks, indicating crosslinking.
- Reduced crystallinity in the regenerated cellulose was observed via XRD compared to pure cellulose.
- Enhanced thermal stability was demonstrated through higher char yields at elevated temperatures with increasing borax concentrations.
- Optical transmittance decreased with increasing borax concentrations due to interactions with tetrahydroborate ions, potentially obstructing light.
- The crosslinked hydrogels exhibited a porous structure via SEM, contrasted with the compact structure of the uncrosslinked hydrogels.
- Water absorption and swelling abilities significantly increased with increasing borax concentrations.
- Antimicrobial efficacy was observed against gram-positive bacteria with varying degrees of reduction depending on borax concentration.
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