Preparation And Properties Of Polysaccharide Hydrogels

Hydrogels are hydrophilic polymers with three dimensional network structure connected by various physical or chemical crosslinks.Because its structure contains a large amount of water,it is widely used in biological tissue engineering,drug delivery and sensor.Natural polysaccharides have good biocompatibility,green safety and abundant sources,which can be used to prepare hydrogels.However,most polysaccharide hydrogels have poor mechanical properties and single properties due to the lack of effective energy dissipation mechanism.In order to solve the above problems,the multifunctional polysaccharide hydrogel with high tensile,anti-fatigue,self-healing and electrical conductivity was prepared by ions cross-linking them with polysaccharides in this paper.And it was used as a strain sensor to detect human motion.Specific researchs were divided into the following two parts:In the first part,the double physically cross-linked networks hydrogels(HPAAm/GG-Ca²⁺DN hydrogel)were prepared,in which acrylamide（AAm）、stearyl methacrylate（SMA）and gellan gum（GG）were used as raw material.The hydrogel has good toughness,fatigue resistance,notch insensitivity and electrical conductivity.The fracture tensile stress of hydrogel was 1030.50 k Pa,the fracture tensile strain was1885.00%,the toughness was 11180.00 k J/m³,and the elastic modulus was 48.02 k Pa.The introduction of Ca²⁺not only enhanced the mechanical properties of hydrogels,but also provided electrical conductivity for hydrogels.Based on its excellent electrical conductivity and mechanical properties,hydrogel could be used for real-time monitoring of human activities,including wrist,finger and elbow movements.In the second part,polyvinyl alcohol（PVA）,hydroxyethyl acrylate（HEA）and?-carrageenan（?）were used as monomers to prepare hydrogels through free radical polymerization and freeze-thawing,which showed excellent mechanical properties,self-recovery,anti-fatigue,self-healing and electrical conductivity.The fracture tensile stress of hydrogel was 625.77 k Pa,the toughness was 1848.04 k J/m³.Hydrogels demonstrated excellent self-recovery and fatigue resistance without external stimulation.The presence of calcium ions made hydrogels conductivity.As such,it could be used to monitor real-time and repetitive movements of the human body,including wrist,elbow,fingers and knees.The excellent mechanical properties and electrical conductivity of hydrogels make them ideal candidates for flexible strain sensors,In this paper,from the hydrogel network structure design,polysaccharide hydrogels were prepared by introducing different interaction into the hydrogel structure,it was endowed good mechanical properties.Polysaccharide hydrogels have good electrical conductivity and it could be used as sensors to monitor the mechanical activity of human joints and physiological health.