Preparation And Properties Of Double Crosslinked Temperature-sensitive High-strength Hydrogel Based On Chitosan Macromolecular Crosslinker

First,chitosan(CS)was used as a multifunctional macromolecular crosslinking agent,and N-isopropyl acrylamide(NIPAM)was used as the monomer,double cross-linked poly(N-isopropyl acrylamide)(PNIPAM)hydrogel was made by free radical polymerization.Then the influence of the reaction temperature,reaction time,N,N-methylene acrylamide(BIS)dosage,CS dosage,potassium persulfate(KPS)dosage and solid content on the mechanical properties of the hydrogel were studied.All of the hydrogels had good thermo-sensitive properties.The study of mechanical properties showed that the BIS dosage,CS dosage and solid content had a great influence on the mechanical properties of the hydrogel.At the same time,compared to PNIPAM hydrogel which only usd BIS as crosslinking agent,the new kind of PNIPAM hydrogel had much better mechanical properties.Second,in order to improve the bonding strength,1-(3-dimethyl amino propyl)-3-2-ethyl carbon imine hydrochloride(EDC),N-hydroxy succinimide(NHS)and methylacrylic acid(MAA)were used as the acylating reagent,methyl acryloyl chitosan(CS-MA)was prepared by N-acylation reaction to replace electrostatic interaction between CS and MAA with amide bond.Then the CS-MA and CS was used as multifunctional macromolecular crosslinking agent and NIPAM was used as monomer,double cross-linked PNIPAM hydrogel was successfully prepared by free radical polymerization.The influence of CS-MA dosage,the crosslinking agent dosage,KPS dosage and solid content on the mechanical properties,hydrogel swelling,de-swelling properties and thermo-sensitive properties were studied.All hydrogels have good thermosensitive properties.The study of mechanical properties showed that CS-MA dosage,crosslinking agent dosage and solid content had a great influence on the mechanical properties of the hydrogel.At the same time,compared with PNIPAM hydrogel crosslinked with CS and BIS,the new kind of hydrogel had much better mechanical properties.