Advanced carboxymethyl chitosan/polyvinyl alcohol films functionalized with Aloe vera rind extract exhibiting enhanced mechanical and antimicrobial properties

Abstract Chitosan possesses intrinsic antimicrobial activity, whereas Aloe vera leaves are rich in antioxidants and phenolic compounds that can enhance polymeric bioactivity. In this study, advanced carboxymethyl chitosan/polyvinyl alcohol (CMCS/PVA) films functionalized with Aloe vera rind extract (RE), a rarely explored bioactive byproduct, were developed and evaluated for their structural, mechanical, and antibacterial properties. O -carboxymethyl chitosan ( O -CMCS) and N , O -carboxymethyl chitosan ( N , O -CMCS) were synthesized from 90%-deacetylated chitosan, with degrees of carboxymethylation of 86.6% and 107.6%, respectively. Among tested solvents, an ethanol/water (4:1 v/v) mixture proved the most effective solvent for extracting phenolic and non-phenolic antioxidants from Aloe vera rinds. Incorporation of up to 20% RE enhanced the tensile performance of CMCS/PVA films, with RE/ N , O -CMCS/PVA showing greater strength than RE/ O -CMCS/PVA. Ethanolic RE exhibited stronger antibacterial activity against Propionibacterium acnes ( P. acnes ) than Staphylococcus aureus ( S. aureus ). The 20%-RE/ O -CMCS/PVA inhibited bacterial growth to the greatest extent, whereas the 10%-RE/ N , O -CMCS/PVA film was as effective as the 15%-RE/ O -CMCS/PVA films. Among all tested formulations, the 10%-RE/ N , O -CMCS/PVA film demonstrated the optimal combination of mechanical strength, hydrophilicity, and antimicrobial efficacy. These findings highlight Aloe vera rind as a sustainable source of functional additives and emphasize the key role of CMCS substitution patterns in tuning polymer network interactions. The developed composite films provide a green and multifunctional platform for eco-friendly bioactive film applications, exhibiting enhanced mechanical and antimicrobial properties, with potential relevance to advanced functional film platforms.