Preparation And Properties Of Silver Nanowires Core@Shell Structure And Its Polvmer Dielectric Composites

Polymer-based dielectric nanocomposites possess excellent dielectric properties while maintaining good mechanical properties,which have raised wide attention in many felds such as flexible electronics,new displays,bioengineering,etc.In this paper,Polydimethylsiloxane(PDMS)was used as the matrix material and silver nanowires(AgNWs)as the main part of the inorganic filler.The three two-phase composites:AgNWs@SiO2?AgNWs@Al2O3 and AgNWs@PDA with the core@shell structure were respectively prepared by introducing a transition layer to prevent the formation of a conductive network.We mainly explore the formation conditions and morphology of different shell layers and study the effects of different shell layers and different proportions of fillers on the micromorphology,thermal stability,glass transition temperature and dielectric,hydrophobic,and electromechanical properties.(1)AgNWs with large aspect ratios was prepared by polyol reduction method,and the amorphous SiO2 and Al2O3 layer were coated on AgNWs by sol-gel method,and the organic polydopamine(PDA)coating layer was obtained by self-polymerization of dopamine.The thickness of the coating layer was controlled by changing the amount of the raw material.These composite fillers of core AgNWs(70 nm)@shell coating(10?20 nm)were successfully synthesized.(2)The three composite fillers can effectively improve the dielectric properties of PDMS by enhancing the interfacial polarization effect,and can increase dielectric constant while maintaining low dielectric loss.In particular,20 wt%AgNWs@SiO2/PDMS nanocomposites achieved a dielectric constant of 6.7(about 2.7 times that of pure PDMS)and a very low dielectric loss of 0.02 at 1 KHz.(3)All of the three composites exhibited good hydrophobic properties,and the contact angle improved with increasing filler content because the incorporated fillers increased the film roughness.When the filling amount reaches 20 wt%,the contact angle of the composite film is about 128°,which is 13° higher than that of pure PDMS.Large contact angles could facilitate their use in electro wetting devices.(4)The increase of the electromechanical sensitivity ? could be achieved in the three composites.In particular,10 wt%of AgNWs@PDA/PDMS nanocomposites have a ? value of 78.Compared with pure PDMS,the ? value is improved by two orders of magnitude,which has certain application potential on dielectric elastomers.