Preparation And Sensing Applications Of Polyvinyl Alcohol Based Conductive Hydrogel

Conductive hydrogels are a kind of materials with good electrochemical,excellent mechanical properties,and high processability.In addition,conductive hydrogels have biocompatible properties,which makes them promising for wearable electronic devices,electronic skin,human-computer interaction and other fields.However,the preparation of hydrogel electronic sensors with excellent mechanical properties,high sensitivity and wide detection range still remains challenging.To solve this problem,in this work,polyvinyl alcohol was used as the polymer matrix to explore how to effectively construct conductive composite hydrogels with different network structures,and their sensing applications were studied.The main work is as follows:Firstly,a single network conductive composite hydrogel with polyaniline doped polyvinyl alcohol was prepared.Using polyvinyl alcohol as the main chain of polymer,glutaraldehyde as the chemical crosslinking agent,phytic acid as the dopant and catalyst,polyaniline conductive filler was uniformly grown in hydrogel matrix by in-situ polymerization method.The hydrogel sensor has excellent tensile strain sensitivity（GF=3.4,0-300%）and compressive stress sensitivity(0.62 k Pa^-1,0-1.0 k Pa),excellent mechanical strength（1.2 MPa,670%）,outstanding compressive fatigue resistance（1500cycles）.It can be applied to human motion detection and sound recognition,and realize real-time monitoring of dynamic pressure.In order to further widen the stress monitoring range and enhance the mechanical strength,polyvinyl alcohol was used as the flexible main chain of polymer,sodium carboxymethyl cellulose as the ductile side chain,tannic acid as the reinforcement.MXene,a two-dimensional conductive medium rich in hydrophilic groups.A pure physical cross-linked double network conductive hydrogel was prepared by a simple freezeing-thawing method.The prepared hydrogel strain sensor has a wider strain detection range（0-700%）and good sensitivity（GF=2.9）.In addition,the sensor has higher mechanical strength（1.8 MPa,740%）,better tensile fatigue resistance（3000cycles）,and can monitor human movement behavior and sense all kinds of small external pressure changes.In this work,the sensing performance of polyvinyl alcohol based hydrogel was regulated by manipulating its network structure,which provides a new idea for hydrogel preparation of wearable flexible electronic devices.