Synthesis And Dual-signal Sensing Performance Of Polyacrylamide Based Composite Hydrogels

Recently,the hydrogels have been widely used in human-machine interfaces,electronic skins due to their flexibility,controllable mechanical properties,excellent elasticity and electrical modification.However,the development of electronic skins with multi-signal monitoring behavior based on hydrogels is still a challenge.In this paper,acrylamide was used as the monomer,and thermo-volume-reversible monomer N-isopropylacrylamide and natural polymer chitosan with antibacterial properties as composite objects.By preparing triple-network and double-network hydrogels,the multi-functionalization of electronic batch skin is realized.FTIR,SEM and other methods were used to characterize the products,and the swelling performance,mechanical properties,conductivity sensitivity,and pressure-temperature dual signal monitoring performance were tested.Firstly,the hydrogel with thermal sensitive properties was prepared by the combination of polyacrylamide and N-isopropylacrylamide with thermotropic volume transformation.And the thermal response point could be adjusted to the human body temperature around.Meanwhile,a multifunctional three network ionic conductive hydrogel was successfully prepared by using polyvinyl alcohol/graphene oxide and Fe3+crosslinked polyacrylic acid double physical network hydrogel as the complex medium.FTIR test showed that triple network was successfully compounded and there was no interference among them.Mechanical performance test illustrated that the combination of the three networks improved the mechanical tolerance of hydrogels,and the introduction of ions and graphene oxide introduced excellent conductivity and stability.Secondly,a double network ionic conductive organohydrogel was prepared by using a acrylamide monomer and a natural polymer chitosan,which has excellent antibacterial properties.The glycerol molecules in glycerol/water binary solvent reacted with the citric acid at high temperature firstly,so that the glycerol with polyhydroxyl molecules was immobilized.The residual hydroxyl of the molecule imparted the hydrogel with strong adhesion capacity.The mechanical properties test showed that the introduction of citricacid molecules increased the tensile limit of hydrogels,and enhanced the antibacterial activity of hydrogels.The remaining unreacted citric acid molecules induced the reduction of graphene oxide so that the appearance of conductivity.Moreover,the hydrogel can maintain flexibility and electrical sensitivity at-10°C.The results show that the two kinds of hydrogels have excellent properties,such as excellent electrical conductivity,mechanical recoverability,low swelling and pressure temperature dual signal monitoring behavior.The three network conductive hydrogel prepared has a wide range of monitoring performance(~5 kPa)for the pressure,and the prepared polyacrylamide/chitosan double network ion organic hydrogel has good tensile properties(500%).Moreover,the organohydrogel exhibits long-term moisture,frost resistance(-10°C)and antibacterial properties.The developed triple network conductive hydrogel sensor could monitor the change of pressure signal,and the dual network hydrogel is more suitable for monitoring the tensile signal generated by large-scale deformation movement.