Preparation And Properties Of Multicrosslingked Network Chitosanbased Composites

Chitosan-based composite film materials have good biodegradability,biocompatibility,and sustainability,are widely used in food packaging,tissue engineering,drug carriers,and wastewater purification.However,its poor mechanical properties and poor toughness limit its application.In this paper,three kinds of chitosan-based composite films were prepared by simple physical and chemical modification.The internal structure was constructed through the multi-crosslinking network,and the mechanical properties of chitosan-based composite films were regulated,and the mechanism of network structure was revealed.The properties of UV resistance,anti-oxidation and antibacterial properties of the composite films were studied.The main contents are as follows:(1)Preparation and research of chitosan/hyperbranched polyethyleneimine/iron ion composite film.By introducing hyperbranched polyethyleneimine,a flexible polymer,a hydrogen bond network structure was constructed inside the composite film,and the elongation at break and toughness of the chitosan film were regulated.When the content of hyperbranched polyethyleneimine was 20%,the elongation at break and toughness were 92.5%,15.3 MJ/m~3,respectively.Compared with the 10.3%elongation at break of theIIIchitosan film,the elongation at break increased by 798.1%.By introducing iron ions to form a synergistic network of metal coordination bonds and hydrogen bonds inside,the tensile strength can be improved while maintaining a high elongation at break.The introduction of hyperbranched polyethyleneimine and iron ions can also improve the antibacterial properties of the composite films against Escherichia coli and Staphylococcus aureus.(2)Preparation and research of chitosan/oxidized tannic acid composite film.The composite film with synergistic chemical network and hydrogen bond network was constructed by Schiff base reaction between chitosan and oxidized tannic acid,and the tensile strength of the composite film was improved.The tensile strength of the composite film was 80.7 MPa after adding 20%tannic acid,and the tensile strength of the composite film was 84.0 MPa with the addition of3%oxidized tannic acid.Compared with the tensile strength of chitosan film of42.6 MPa,the tensile strength was increased by 89.4%and 97.2%,respectively.Meanwhile,the effects of adding tannic acid and oxidized tannic acid on UV resistance properties,antibacterial properties and antioxidant properties were also studied.the UV resistance and antibacterial properties were studied.(3)Preparation and research of chitosan/caffeic acid and chitosan/caffeic acid/iron composite films.The phenolic hydroxyl group of caffeic acid is auto-oxidized to form a chemical bond between the o-quinone structure and the chitosan molecule,forming a synergistic network of chemical bond,metal coordination bond and hydrogen bond,and regulating the mechanical properties of the composite film.The formation and regulation mechanism of composite film network structure.The effect of the addition of caffeic acid and iron ions on the UV blocking performance was studied.After adding 0.3 mmol of caffeic acid,the transmittance of the composite solution at 365 nm was reduced by 99.38%compared with the chitosan solution.The UV resistance of solution at 365 nm could further improved by introducing iron ions.The composite film has potential application value in the field of UV resistance and antibacterial packaging.