Preparation And Characterization Of Electric Field Sensitive PVA/PSS Composite Hydrogels

Hydrogel is a kind of three-dimensional network polymer composed of hydrophilic polymer chains connected by physical or chemical connections.The unique network structure makes hydrogels quite hydrophilic,bio-compatible and similar to tissues of living organisms.Therefore,hydrogels are often used in bio-medicine,tissue engineering,drug delivery,soft electronics and many other fields.In recent years,intelligent hydrogels have attracted much attention.In all kinds of intelligent hydrogels,electric field sensitive hydrogels have been favored by researchers because of the easy application and control of electric field,a wide range of selectable materials,a lot of simple preparation methods and pretty broad application fields and prospects.In this study,a PVA/PSS semi-interpenetrating polymer hydrogel was prepared by a simple blend of strong polyelectrolyte poly(styrene sodium sulfonate)(PSS)into the weak polyelectrolyte poly(vinyl alcohol)(PVA)hydrogel,and its properties were improved by compositing carboxyl multi-walled carbon nanotubes.Based on the aldol condensation reaction between PVA and GA,PVA-GA chemical crosslinking hydrogel could be successfully prepared.But the electric field sensitivity of the hydrogel was very poor.Compositing PSS in the preparation of PVA-GA chemical hydrogel by simple blending,could significantly increase the electric field sensitivity of the hydrogel.When PSS/PVA=1/8,the bending angle of hydrogel in electric field(E=0.67V/mm)for 60 seconds was 47 °,which was nearly 12 times higher than that of hydrogel without PSS.In a certain range,the higher the PSS content was,the better the improvement effect was.While PSS greatly reduced the mechanical properties of the hydrogels.When PSS/PVA=1/8,the elastic modulus of the hydrogel pre-equilibrated in deionized water decreased by nearly 1/3.Adding carbon nanotubes into the PVA/PSS composite hydrogel could improve the electric field sensitivity and mechanical properties of the hydrogel to some extent.The improvement on the former was much more obvious.For example,the bending angle of C1 hydrogel in electric field(E=0.67V/mm)for 60 seconds was 78°,which was 20% higher than that of C0 without carbon nanotubes.Simple experiments showed that the electric field sensitive composite hydrogel containing PVA/PSS and CNT/PVS-PSS could be used as an energy conversion device,which indicating that the hydrogels had the potential to be applied as artificial muscles and chemical valves.