Tough and Biodegradable Gelatin-Based Film via the Synergistic Effect of Multi-Cross-Linking

Abstract

Large amounts of petroleum-derived packaging film waste cause environmental problems and threaten human health. In this study, a multi-cross-linked biodegradable film containing gelatin, dialdehyde oligo-chitosan (DOC), and polyvinyl alcohol (PVA), with excellent mechanical properties, was fabricated via a facile process. The DOC simultaneously acted as an antioxidative and antimicrobial component and a crosslinker to covalently crosslink the gelatin matrix to form the first gelatin network. PVA cross-linked via its crystalline domains acted as the second network, interpenetrating the first gelatin network. The film with such a structure contained multi-cross-linking of hydrogen bonds, covalent bonds, and crystalline domains that all could act as sacrificial bonds to dissipate energy. Therefore, the fabricated film exhibited high mechanical strength and toughness. Additionally, it also demonstrated good light transmittance, improved moisture resistance, and biodegradability in natural soil, and its food preservation efficiency was comparable to that of commercial polyethylene materials. The fabrication process is facile and harmful solvent-free; all these properties make the film a promising alternative to conventional non-biodegradable petroleum-derived packaging films for food preservation.

Research Progress of Polyvinyl Alcohol Water-Resistant Film Materials

“…Chen et al [ 67 ] fabricated a multi-crosslinked biodegradable film containing gelatin (Ge), dialdehyde oligomeric chitosan (DOC), and PVA with excellent mechanical properties. DOC acts as both an antioxidant and antimicrobial component and a cross-linking agent to covalently cross-link the gelatin matrix to form the first gelatin network.…”

A Transient Pseudo‐Capacitor Using a Bioderived Ionic Liquid with Na Ions

“…The BD BOD_PIL reached 70% in 6 days, whereas the maximum BDBOD_IG was 54% within 28 days. PVA is known as a biodegradable polymer 31,[52][53][54][55] , however, the biodegradation rate of PVA is moderate in the OECD test 56 . Therefore, PVA could slow the biodegradation rate of IG.…”

Recent progress in fabrications and applications of functional hydrogel films

“…54 The dynamic fracture and reformation of physical crosslinks dissipate vast energy and afford the hydrogel film with excellent mechanical properties. 27,28,[32][33][34][35][36][37][38] More interestingly, the rational design of these dynamic crosslinks in the matrices leads to remarkable self-healing properties of hydrogel films. 8,65,66 In a seminal work, Lyon et al demonstrated the autonomous healing of micron-sized defects in a layer-by-layer assembled hydrogel films containing polyanion-polycation interactions.…”

“…23 Meanwhile, various facile methods have been developed to prepare functional hydrogel films as freestanding films or coatings on substrates. [24][25][26][27][28][29][30][31][32][33][34][35] These films have the similar chemical/physical characteristics to other hydrogel-based materials, such as high water content, biocompatibility, and stimuli responsiveness. Furthermore, hydrogel films show faster response, high flexibility and adaptivity, and versatile capacities of integrating with other functional components.…”

“…Hydrogel films are usually made of thin layers of hydrophilic polymer networks such as natural derived (e.g., chitosan, gelatin, carrageenan and alginate) or synthetic polymers (e.g., polyvinyl alcohol [PVA], polyacrylic acid [PAAc], polyacrylamide [PAAm], and poly( N ‐isopropyl acrylamide) [PNIPAm]) while maintaining high swollen state in aqueous conditions 23 . Meanwhile, various facile methods have been developed to prepare functional hydrogel films as freestanding films or coatings on substrates 24–35 . These films have the similar chemical/physical characteristics to other hydrogel‐based materials, such as high water content, biocompatibility, and stimuli responsiveness.…”