The Grafting Of PLA Surface Temperature-sensitive Interpenetrating Network Hydrogel And Its Application In Smart Dressing

Wound dressings can cover and protect damaged areas when the skin is injured.The excellent hygroscopicity of hydrogel dressings can create a moist environment conducive to wound healing.However,ordinary hydrogel dressings cannot recognize the difference between different stages of wound healing,therefore,it is very necessary to develop smart dressings that can control and adjust the moisturization and permeability of the wound surface at different stages of wound healing.Poly(N-isopropylacrylamide)(PNIPAAM)is a smart polymer material that can sense changes in external temperature and produce reversible changes in volume.Applying it to the field of wound dressings can not only maintain a moist environment on the wound surface,but also intelligently adjust the moisture permeability and heat dissipation behavior of the fabric at different stages of wound healing,which can promote the growth of wound cells and wound healing.In this paper,biodegradable polylactic acid(PLA)non-woven fabric is used as the substrate,polyacrylamide/poly(N-isopropylacrylamide)(PAAM/PNIPAAM)interpenetrating network is used as the hydrogel system.The method of combining double bond pretreatment and ultraviolet light grafting is grafted on the surface of PLA non-woven fabric with a temperature-sensitive interpenetrating network hydrogel system with a certain fastness,which is constructed to be intelligent with controllable moisture permeability with environmental temperature changes dressing.The main research contents and results of this paper are as follows:(1)Unsaturated double bond pretreatment on the surface of PLA non-woven fabric.This article firstly uses resorcinol diglycidyl ether and acrylic acid as raw materials to prepare resorcinol diglycidyl acrylate through a ring-opening reaction.The PLA non-woven fabric is pretreated by high-temperature heat treatment.The surface introduces reactive unsaturated double bonds.According to infrared spectroscopy,acrylate groups have been successfully introduced into the surface of PLA fabrics.The best synthesis process of resorcinol diglycidyl acrylate is: triethylamine is used as a catalyst,the ring-opening reaction temperature is 120 ℃,and the ring-opening reaction time 6h;The best process for introducing unsaturated double bonds on the surface of PLA non-woven fabrics is: the concentration of resorcinol diglycidyl acrylate is 10%,the heat treatment temperature is 120 ℃,and the heat treatment time is 3min.(2)Grafting of single network hydrogel on the surface of PLA non-woven fabric.Under ultraviolet light irradiation,the monomer acrylamide(AAM and)N-vinylpyrrolidone(NVP)was grafted on the surface of the unsaturated double bond pretreatment PLA non-woven fabric and the grafting process was explored.The experimental results show that ultraviolet light can successfully initiate the grafting of the mono-network hydrogel on the surface of the PLA non-woven fabric pretreated by the unsaturated double bond.When acrylamide is the grafting monomer,the reaction system has higher reactivity and efficiency.PLA The best process for surface PAAM hydrogel grafting is: when the concentration of AAM monomer is 10%,the concentration of photoinitiator 1173 is 1%,and the amount of crosslinking agent is 1%,the unsaturated double bond pretreats PLA fabric under ultraviolet light.After grafting for 20 minutes,the fabric can obtain the maximum grafting rate.(3)Grafting of temperature-sensitive interpenetrating network hydrogel on the surface of PLA non-woven fabric.The temperature-sensitive PNIPAAM hydrogel is introduced into the above-mentioned AAM single-network hydrogel system in the form of an interpenetrating network,and its influence on the moisture absorption and moisture permeability of the fabric is explored by adjusting the concentration of PNIPAAM in the interpenetrating network.The experimental results show that the surface of PLA-PAAM/PNIPAAM fabric has a rich porous structure,and there is a volume phase transition phenomenon at 34.98 ℃.When the concentration of PNIPAAM is 2.5%,the PLA-PAAM/PNIPAAM fabric is prepared with high moisture absorption at low temperature and high moisture permeability at high temperature.(4)Research on the application of PLA-PAAM/PNIPAAM fabric in the field of wound dressings.The biocompatibility of PLA-PAAM/PNIPAAM dressing and its effect on wound healing were explored through the L-929 cell proliferation experiment and the construction of mouse skin defect model.The experimental results show that PLA-PAAM/PNIPAAM fabric has no cytotoxicity and good biocompatibility when applied to wound dressings.Compared with ordinary medical gauze dressings,the dressing has more complete epidermal tissue growth on the 7th day of wound recovery.On the 14 th day of wound healing,the completeness of the wound surface was the best,and the hair follicle structure was clearly visible,indicating that the dressing had better wound healing effects than ordinary medical gauze dressings.