Preparation Of MXene Based Double Network Conductive Hydrogel And Its Application In Flexible Sensors

Conductive hydrogels have great prospects in flexible sensor applications due to their inherent stretchability,reversible flexibility and unique conductivity.However,most conductive hydrogels at this stage still have problems such as poor mechanical properties,poor sensitivity,poor conductivity and poor degradability.Therefore,in order to solve these problems,there is an urgent need for strain sensors with high tensile,adhesion,and high sensitivity characteristics.MXene can be used as a candidate conductive filler because of its hydrophilic and conductive properties.However,at present,the development of MXene-based hydrogel flexible sensors is mainly affected by the self-stacking of MXene,resulting in the degradation of hydrogel mechanical properties and sensing performance,in this context,we designed and prepared three dual-network gel systems with different structures to optimize the design of the sensors from different angles.The specific work is as follows:（1）MXene（Ti₃C₂T_x）composite polyvinyl alcohol（PVA）/polyvinyl alcohol pyrrolidone（PVP）dual network hydrogel（MPP-h）flexible strain sensor was prepared.Homogeneously distributed hydrophilic MXene nanosheets form a three-dimensional conductive network in the hydrogel,enabling flexible sensors to have high sensitivity.The strong interaction between the double-network hydrogel matrix and MXene greatly improves the mechanical properties of the hydrogel.The obtained nanocomposite hydrogel has good tensile properties（2486%）,toughness and resilience.This flexible pressure sensor has extremely high sensitivity,a wide response range,a fast response speed（210 ms）and a low detection limit.In addition,hydrogel-based flexible sensors have high sensitivity characteristics and durability,can be used to monitor the all-round movement of the human body,and have potential application prospects in facial expression and speech recognition,handwriting verification,health diagnosis,and wearable electronics.（2）A conductive binetwork MXene/SA/PVA hydrogel（MSP-h）consisting of polyvinyl alcohol（PVA）,sodium alginate（SA）and MXene was constructed by a simple method.The resulting hydrogels with double network characteristics show high tensile properties（up to253%）and excellent fatigue resistance（up to 800 cycles）.What’s more,strain sensors based on MSP-h have good sensing sensitivity,fast response time（230 ms）,and can be detected even at very slight strain of 0.2%,so the detection limit is low.It can be used to assemble flexible sensors to monitor human movement.（3）MXene/PAM/SA double-network（DN）organic hydrogel（MPSOH）was successfully prepared by combining MXene nanosheets with polyacrylamide（PAM）and sodium alginate（SA）and replacing them in glycerol.The prepared MPSOH showed excellent antifreeze ability（-40°C）and long-lasting moisturizing ability（6 days）at low temperature.In addition,the sensor has excellent mechanical properties（tensile strain 1579%）,self-adhesiveness,excellent sensitivity（strain coefficient of 49.92）,low detection limits（1%strain）and excellent fatigue resistance（800 cycles at 30%strain）.As a result,hydrogels can be assembled into flexible wearable sensors that can be used to monitor human movement and other activities in real time.