Preparation And Characterization Of Gelatin/Cellulose High-Strength Thermosensitive Hydrogels

In functional polymers,the surface properties of poly-N(isopropylacrylamide)(PNIPAM)change with temperature,and the change in properties occurs at around 32?,called the lower critical solution temperature(LCST).Because the LCST is close to human body temperature,PNIPAM is widely concerned.Gelatin is a natural polymer with biocompatibility,low cytotoxicity and a large number of reactive functional groups.It is a good choice for graft modification.Cellulose is a long-chain,high molecular weight homopolymer that has received extensive attention due to its abundant reserves,high strength,non-toxicity,and biodegradability.Thus,combining the respective characteristics and deficiencies of the three,a composite gel with two-component modification and enhanced mechanical strength of the temperature-sensitive gel was prepared1.A poly(oxidized cellulose-co-acylated gelatin-co-N-isopropylacrylamide)temperature sensitive hydrogel(DGN)was prepared.First,a graft ratio of 86.8%acylated gelatin(GelMA)and an oxidation degree of 8.14 mmol/g of oxidized cellulose(DAC)were successfully prepared.DGN hydrogels were prepared by NIPAM self-polymerization and Schiff base reaction of DAC.The structure of the target product was confirmed to be DGN by Fourier transform infrared spectroscopy(FT-IR),nuclear magnetic resonance spectroscopy(1H NMR)and the like.2.The effect of GelMA(determined amount of DAC)on the structure and properties of the DGN gel was investigated.The test results showed that when the composite gel is graft modified by GelMA system,the structure of the composite gel will increase with the increase of the ratio of GelMA,the degree of crosslinking will decrease,the gel will become porous and the water absorption performance will decrease.At the same time,the good temperature sensitivity of the composite gel is retained.The tensile strength of the composite gel film was increased by 1.4-2.5 times and the maximum tensile strength was 26.59 MPa.At the same time,it has good biocompatibility.It is indicated that the grafting modification of GelMA system enhances the mechanical properties of poly-N(isopropyl acrylamide).3.The effect of DAC(determined amount of GelMA)on the structure and properties of the DGN gel was investigated.The test results showed that when the composite gel was graft modified by DAC system,the structure of the composite gel increases with the proportion of DAC,the degree of crosslinking increases,the gel becomes compact and the water absorption is enhanced.At the same time,the good temperature sensitivity of the composite gel is retained.The tensile strength of the composite gel film was increased by 1.4-3.7 times,and the maximum tensile strength was 38.78 MPa.At the same time,it has good biocompatibility.It is indicated that the grafting modification of DAC system enhances the mechanical properties of poly-N(isopropyl acrylamide).This composite gel with good mechanical strength,good temperature sensitivity and biocompatibility is expected to further expand the application range of PNIPAM in the field of medical dressings.