Preparation,Characterization And Application Of Polyaniline-based Conductive Hydrogels For Flexible Strain Sensors

With the rapid development of flexible electronics,wearable devices,biomedicine,tissue engineering and other fields,flexible electronic materials with both flexibility and conductivity have become a major trend for furture electronic materials.Conductive polymer-based hydrogels are expected to be one of the promising materials for flexible electronics and other fields due to their flexible construction strategies,controllable mechanical propertiesand electrical conductivity.Therefore,conductive polymer-based hydrogels have attracted extensive attention from researchers.However,the existing conductive polymer-based hydrogels generally suffer from low mechanical strength and single function,which limits their applications in flexible electronics and other fields.By constructing and regulating network structure of conductive polymer-based hydrogels,,this paper thesis aims to improve the mechanical properties of conductive polymer-based hydrogels and expand their functionality and applications.Series of conductive polymer-based hydrogels have been constructed using polyaniline?PANI?as the conductive component,polyacrylic acid?PAA?,poly?N-isopropylacrylamide??PNIPAAm?and polyvinyl alcohol?PVA?as the flexible components.The influence of different flexible components,conductive components and their content on the performance of the hydrogels isstudied.The applications of the hydrogels in flexible strain sensors,pressure sensors,sensor arrays and temperature alarm model systems are demonstrtated.The main contents are as follows.?1?The construction strategy of binary cooperative network is adopted.Amphiphilic block copolymer Pluronic F127 containing double bonds?F127DA?is used as the cross-linking agent.Polyacrylic acid?PAA?hydrogel network and polyaniline?PANI?networks are constructed as the flexible component and conductive component,respectively.The polyacrylic acid/polyaniline?PAA/PANI?hydrogel with ultra-long stretch?1130%?and controlled conductivity was obtained by the in-situ polymerization method.The factors influencing the performance of hydrogels were studied to realize the controllability of the gel properties.The flexible strain sensor constructed with the hydrogel has a high deformation detection range of 0?1130% and a response time of 0.5s.It can be used to monitor the index finger bending,swallowing and other human motions.?2?The construction strategy of binary cooperative network is adopted,and F127DA is used as a cross-linking agent for the flexible substrate of poly?N-isopropylacrylamide??PNIPAAm?hydrogel,which is temperature-responsive and conductive by in-situ polymerization And stretchable?230%?poly?N-isopropylacrylamide?/polyaniline?PANI??PNIPAAm/PANI?hydrogel.The factors influencing the performance of hydrogels were studied to realize the controllability of the gel properties.The flexible strain sensor constructed with this hydrogel has a sensitivity of GF=3.9 and a response time of 0.4s,and can be used to monitor human movements such as index finger movement,swallowing,and pulse.Based on the characteristics of the hydrogel temperature response,a temperature alarm switch system was constructed.?3?The construction strategy of physical blending is adopted,through the all-physical cross-linking method of drying-reabsorbing water.hollow polyaniline microspheres?HPS?as the reinforcing phase and conductive component,and polyvinyl alcohol?PVA?hydrogel as Flexible substrate.a polyvinyl alcohol/hollow polyaniline microsphere?PVA/HPS?hydrogel with high mechanical strength?9.33 MPa?,high stretchability?500%?,electrical conductivity and recyclability is obtained.The factors influencing the performance of hydrogels were studied to realize the controllability of the gel properties.The flexible strain sensor constructed with the hydrogel has a high deformation detection range of 500%and a response time of 0.18s.It can be used to monitor human activities such as finger joint bending,swallowing,and pulse.In addition,based on the piezoresistive effect of hydrogel,a resistive pressure sensor array and a capacitive pressure sensor with sensitivity GF=3.62 kPa^-1can be applied to the sensor array.