Preparation And Properties Of Conductive And Shape Memory Hydrogel

Hydrogels have a wide range of applications due to their excellent biocompatibility and high ductility.As a type of smart hydrogel,shape memory hydrogel is a soft material that responds to external stimuli and can fix temporary deformations and remember the original permanent shape,thus rapidly attracting attention in areas such as drug release,actuators and artificial muscles.However,the absence of conductive media in conventional shape memory hydrogels does not have conductive properties,severely limiting the use of hydrogels in sensors.Therefore,the preparation of a shape memory hydrogel with a conductive function is a very interesting task.The effects of the introduction of cationic chitosan/graphene oxide(GO)on the mechanical properties of hydrogels were discussed in the first part of this paper.The first network was formed between polyvinyl alcohol(PVA)and propanetriol by multiple hydrogen bond bridging,and the second network was formed between cationic chitosan and GO by electrostatic interaction,and the two networks acted synergistically to construct the network structure of the dual network hydrogel.The introduction of the second network as a sacrificial network significantly improved the mechanical properties of the dual network hydrogels,which exhibiting rupture stresses up to 1.6 Mpa,rupture strains greater than 900%,and elastic modulus and toughness of 412 kPa and 6.2 MJ/m~3,respectively.We also performed rheological tests on the hydrogels,which showed that the introduction of the cationic chitosan/GO network improved the crosslinking density within the hydrogels,thus greatly improving their mechanical properties.In the second part of this paper,we investigated the electrical conductivity,freeze resistance,and shape memory properties of PVA-cationic chitosan hydrogels.The cationic chitosan molecule free of chlorine ions gives the hydrogel good electrical conductivity,the hydrogel could light up the LED bulb,and as a sensor to achieve the monitoring of human movement.The formation of a large number of hydrogen bonds between propanetriol and water avoids the formation of hydrogen bonds between water molecules at low temperatures,thus greatly improving the stability of the hydrogel at low temperatures,so that the hydrogel can remain ductile at-20°C.In addition,the hydrogels exhibit excellent thermogenic response shape memory behavior,with the dynamic hydrogen bonding formed by the partial orderly arrangement of PVA molecular chains after deformation,thus achieving the fixation of the temporary shape of the hydrogels and the recovery of the permanent shape.Also.And multiple dynamic physical actions allow the hydrogel to be reshaped after disruption.The excellent conductivity and shape memory properties of hydrogels make it possible to manufacture hydrogel-based temperature alarm devices.