Modification And Actuation/Sensing Studies Of PDMS And PVC Dielectric Elastomers

Dielectric elastomers(DEs)have great application prospect in the fields of flexible actuator(DEA,artificial muscle)and sensor(DES,electronic skin).Although DEA/DES has been partially commercialized,the existing DEA/DES devices have the defects of low dielectric constant and high viscoelasticity of the polymer matrix film,which lead to creep,electrical breakdown,mechanical loss,and viscoelastic hysteresis of the fabricated devices.In this paper,starting from polymer modification and preparation,the purpose is to prepare polyvinyl chloride(PVC)gel and silicone rubber(SR)elastomer with high dielectric,high elasticity and low viscosity,and use it for DEA /DES.The results are as follows:(1)PVC gel has the disadvantages of low dielectric constant and high viscoelasticity,which not only reduces the electromechanical coupling ability,but also weakens the driving/sensing stability.In this chapter,highly substituted cyanoethylcellulose(CEC)was synthesized by Michael addition reaction and filled into PVC gel(PVCg).CEC/PVC composite gel(CEC/PVCg)with high dielectric constant(18.93 @ 1k Hz)and a maximum electromechanical coupling sensitivity(65.88)was obtained by using the orientation polarization of cyano groups.Finally,CEC/PVCg was used to prepare DEA with high force/displacement output and DES with high baseline capacitance and sensitivity.Due to the strong interaction between CEC and PVCg molecules,CEC/PVCg also exhibited extremely low viscoelasticity,and the prepared DEA/DES exhibited high repeatability,excellent stability,and fast electromechanical response properties.(2)The dielectric constant of SR is extremely low,therefore,SR-based DEA often require very high voltage and is often at risk of electrical breakdown and creep.In this chapter,carbon black particles encapsulated with hydroxy-terminated-polydimethylsiloxane(HO-PDMS)are filled into vinylsilane-rich silicone(VRS)to obtain PCB/VRS composite film with enhanced dielectric properties and electrical breakdown properties.Compared with the VRS film,the Young's modulus and dielectric constant of the PCB/VRS composite film containing 5.82 vol.%PCB increase by 613% and 244%,respectively.The encapsulation of PDMS effectively prevents the adjacent CB particles from forming a conductive network,so the resulting PCB/VRS composite has an enhanced breakdown strength of 63.31 V/?m and an attenuation dielectric loss of 0.078,which is beneficial for DEA applications.Triggered by a relatively low electrical field of7.14 V/?m,the PCB/VRS-DEA exhibits better out-of-plane actuations compared to the VRS-DEA: 1.91-fold in flection amplitude,2.79-fold in areal strain,and 4.35-fold in force output.(3)The introduction of fillers not only improves the dielectric properties of the matrix,but also often strengthens the mechanical properties of the matrix,which is not beneficial to the large deformation output of DEA.In this chapter,dopamine-coated zinc oxide(PDA@Zn O)particles were introduced into PVCg,which changed the interaction force between molecules inside PVCg,and obtained PDA@Zn O/PVCg with enhanced dielectric properties and reduced tensile modulus.Compared with PVCg,the PDA@Zn O/PVCg has a maximum decrease of 60.87% in tensile modulus,a maximum increase of 22.72% in dielectric constant,a maximum increase of 156.25%in electromechanical sensitivity,and a maximum increase of 577.37% in breakdown strength.Under a pulsed electric field of 6.54 V/?m,the PDA@Zn O/PVCg planar actuator produces a large-area strain of 33.27%.