Preparation And Properties Of Carbon Nanotubes And Sodium Polyacrylate Conductive Composite Hydrogel

In recent years,conductive hydrogels have been widely used in wearable flexible sensors due to their excellent electrical,mechanical and biocompatibility.However,their poor adhesion and durability will lead to the problems such as instability contact voltage with devices and not easy to store,which limited their use.Therefore,the preparation of a conductive hydrogel with good adhesion and durability has significant application.In this paper,with carbon nanotubes?CNT?as conducting fillers,aluminum glycine?AG?as crosslinking agent,tartaric acid?TA?as crosslinking regulator,and water and alcohol as solvent system,two kinds of composite hydrogels crosslinked by Al³⁺were prepared.?1?With sodium polyacrylate?PAANa?and Carbopol as hydrogel elements,ethylene diamine tetraacetic acid?EDTA-Na2?as chelating agent,we studied the effect of solvent systems which were composed of water and different kinds of alcohol solvents such as ethylene glycol?EG?,glycerol?GLY?and poly?ethylene glycol??PEG,Mw=400?on the conductivity,adhesive properties,water retention and rheological properties.The results showed that adhesive,water retention and rheological properties of the hydrogel were improved with the increase of alcohol solvent content in a certain range,but conductivity was decreased.Compared with different kinds of alcohol solvents,EG/water hydrogel has the greatest conductivity,PEG/water hydrogel had the highest value of storage modulus?G??,loss modulus?G???and consistency coefficient,while GLY/water hydrogel had the best adhesion strength,water retention performance and long-lasting durability.Therefore,GLY could be considered as the most suitable alcohol solvent to be introduced into binary solvent system.This work could play a guiding role in the study of hydrogel properties of similar binary solvent system composed of water and alcohol solvent.?2?With partially neutralized sodium polyacrylate,namely NP-700,as hydrogel element and a binary system composed of water and GLY as solvent system,we studied the effect of the content of CNT,AG and NP-700 on conductivity,mechanical properties,surface adhesion strength,rheological properties,water retention,swelling ratio,strain electrical resistance sensitivity and resistance to low and high temperature condition.The results showed that the prepared hydrogels had the greatest conductivity up to 0.814 S/m,the maximum tensile strength up to 18.26 kPa,the highest breaking elongation up to 1076%,and the maximum compression strength up to 3.523 MPa.The hydrogels also had good water retention and swelling ratio,and showed certain adhesion strength to porcine skin,polylactic acid?PLA?and glass.Good resistance to low and high temperature condition enabled the hydrogels to maintain their original performance when stored at-20?and 50?for 24 h.At the same time,the hydrogels were sensitive to electrical resistance in tensile strain,compression strain and bending strain.The hydrogels could be used for monitoring human body movement such as arm bending,back bending and throat swallowing.