Preparation And Properties Of κ-Carrageenan-based Dual Physically Cross-linked Hydrogels

κ-Carrageenan(κ-CG)is a natural anionic sulfate linear polysaccharide polymer,which has good biocompatibility and temperature-sensitive"sol-gel"transition characteristics.However,the mechanical properties of the traditionalκ-CG-based physically cross-linked hydrogels have limited their further applications.The purpose of this thesis is to construct newκ-CG-based dual physically cross-linked(DPC)hydrogels with enhanced mechanical properties and functionalization,such as pH responsiveness,self-healing ability,and light responsiveness.On this basis,two differentκ-CG-based hydrogels were designed.Firstly,κ-carrageenan/polyacrylic acid(κ-CG/PAA)DPC hydrogels were prepared by"one-pot"method,and zirconium ion was used to promote“sol-gel”transition ofκ-CG.The experimental results showed thatκ-CG/PAA DPC hydrogels had excellent tensile stress of 2.53 MPa,fracture strain of 1381.91%and toughness of 13.40 MJ/m~3.Compared with K~+,the tensile strength of hydrogel was increased by 0.76 times,which verified that dual cross-linking ofκ-CG(double-helical junctions and ion cross-linking)was conductive to high strength and toughness.Moreover,due to the completely physically cross-linking structures,theκ-CG/PAA DPC hydrogels showed self-healing capability.The volume swelling rate ofκ-CG/PAA DPC hydrogels changed significantly in different pH environments.Furthermore,the DPC hydrogels exhibited cytocompatibility and biodegradability.Secondly,κ-carrageenan/cationic polyacrylamide-ammonium molybdate(κ-CG/CPAM-Mo7)hydrogels were synthesized using Mo7 as the photochromic unit.Mechanical properties and UV light-responsiveness of hydrogels were analyzed.After introducing Mo7,the tensile strength was up to 1.83 MPa,which was 0.19 MPa higher than that ofκ-CG/CPAM hydrogel.At the same time,in the light-response experiment,the hydrogels showed fast,controllable UV light-responsiveness,and the pattern printed on hydrogel did not wear out after 100 times of cyclic stretching under a strain of 50%.Furthermore,they could also store uncomplicated QR and ACSII code information,which showed the potential application of theκ-CG/CPAM-Mo7 DPC hydrogels as light storage materials.