Preparation Of Dielectric Polymer-based Nanocomposites Via Reversible Addition Fragmentation Chain Transfer Polymerization

In recent years,with the continuous development of electronic industry,miniaturization,lightweight and high energy storage efficiency have gradually become the focus of the field,which requires materials to show high energy storage,high thermal conductivity and good processability,etc.Polymer-based nanocomposite is the hotspot of current research.However,the addition of inorganic fillers generally causes increased dielectric loss,decreased breakdown strength and processability of the composites,further leading to the decrease of energy storage properties.This paper mainly focuses on improving the interface compatibility between filers and polymer matrix so as to improve the comprehensive performance of the nanocomposites via reversible addition fragmentation chain transfer?RAFT?polymerization.In the first part:we report a novel method to enhance energy storage efficiency and breakdown strength of high-k nanowires?NWs?based poly?vinylidenefluoride-hexafluoropropylene??P?VDF-HFP??nanocomposites.Ba_0.7Sr_0.3TiO₃ NWs were synthesized by a hydrothermal method and their surface was grafted by a layer of poly?pentaflurophenyl acrylates??PPFPA?via in situ RAFT polymerization.Compared with the addition of as-prepared NWs,the incorporation of PPFPA encapsulated NWs apparently enhanced the breakdown strength of the nanocomposites.On the other hand,the incorporation of PPFPA encapsulated NWs results in much lower dielectric loss at low frequencies and higher energy storage efficiency of the nanocomposites.In the second part:an in situ grafting approach was designed to fabricate thermally conductive,electrically insulating and post-melt processable polystyrene/BN nanosphere?BNNS@PS?nanocomposites by initiating styrene?St?on the surface functionalized BNNS via RAFT polymerization.The nanocomposites exhibit significantly enhanced thermal conductivity.For example,at a St/BN feeding ratio of 5:1,an enhancement ratio of 1375%is achieved in comparison with pure PS.Moreover,the dielectric properties of the nanocomposites show a desirable weak dependence on frequency and the dielectric loss tangent of the nanocomposites remains at a very low level.More importantly,the nanocomposites can be subjected to multiple melt processing to form different shapes.Our method can become a universal approach to prepare thermally conductive,electrically insulating and melt-processable polymer nanocomposites with diverse monomers and nanofillers.