Preparation Of Polyacrylonitrile-based Hydrogel And Its Application In Flexible Sensing

With the rapid development of artificial intelligence（AI）and Internet of Things（Io T）,the field of flexible sensing has gradually attracted extensive research interest of researchers As an important part of the sensor,the flexible sensor not only overcomes the limitation of the environment on the detection equipment,but also expands the application of the sensor in the field of human motion monitoring and medical care Due to its adjustable mechanical strength and non-biotoxicity,hydrogels successfully achieve a seamless combination between biology and electronics However,the existing hydrogel sensors usually have poor mechanical properties and require external power or batteries,which limit their applications in the field of flexible sensing Therefore,it is necessary to develop a hydrogel sensor with the advantages of easy preparation,low cost,high elasticity and self-powered for flexible sensing field Based on applied in the field of flexible sensing hydrogel sensor as a starting point,the polyacrylonitrile-based piezoelectric hydrogel with good mechanical-electric response properties and flexibility was prepared by combining the mechanical-electric response properties of piezoelectric polymer PAN with the inherent flexibility of hydrogels and the inherent broad-spectrum adhesion of zwitterionic hydrogelsIn this study,the polyacrylonitrile-based self-powered hydrogel（PVA-PAN）based on polyvinyl alcohol（PVA）,acrylonitrile（AN）,sodium p-styrene sulfonate（Na SS）,acrylamide（AAm）as raw materials,N,N’-methylene bisacrylamide（MBA）as crosslinking agent is prepared by solution polymerization The dipole interaction between the PAN chains and the hydrogen bond between PVA and PAN segments promoted the PAN to the planar zigzag conformation,and the maximum piezoelectric coefficient d₃₃ was 32 p/CN It has a similar young’s modulus value to skin（23±0 20 MPa）and good stretchability（408±0 784%）Due to the stress-induced polarization effect,the self-powered hydrogel can generate an electrical output of about 60 m V The V-T curve shows that the hydrogel can accurately detect various human activities（such as joint movement,step frequency,etc）through the change of voltage signal,which provides theoretical guidance for its application in artificial skin,human health detection,medical diagnosis and other fieldsIn order to solve the problem that hydrogel sensor can not accurately obtain skin deformation due to the lack of adhesion performance In this study,The polyacrylonitrile-based adhesive piezoelectric hydrogel（PNx Dy Az）was prepared by introducing cationic monomer（methacrylatoethyl trimethyl ammonium chloride（DMC））into the polyacrylonitrile-based piezoelectric hydrogel and combining it with anionic monomer（Na SS）The introduction of cationic monomer（DMC）not only improves the crosslinking strength of hydrogel network through electrostatic interaction with cationic monomer（Na SS）,but also endows hydrogel with excellent adhesive properties The synergistic effects of dipole-dipole interaction,hydrogen bond and electrostatic interaction in PNx Dy Az hydrogel network not only endows hydrogel with the skin-like Young’s modulus（4 47±3 79 k Pa）,excellent stretchability（499±9 54%）and high elasticity,but also endows it with excellent mechano-electric response performance It can generate stable electrical signal output（～65 m V）in 3000external stress loading-unloading cycles,which provides a new idea for its application in flexible sensing,human motion monitoring and medical care.