CHAPTER 10: Ionic Liquid-modified Poly(Vinylidene Fluoride): from High Performance Anti-static Materials to Flexible Dielectric Materials

Semi-crystalline poly(vinylidene fluoride) (PVDF) is of great significance in the family of fluorine polymers and its modification has always been an active area of research both in industrial and academic research fields. Raw PVDF is known to crystallize into a non-polar crystal form that is insulative and hydrophobic, and has a low dielectric constant, restricting its direct practical application and thus stimulating huge research interest in the modification of PVDF by means of physical or chemical methods. On the other hand, room temperature ionic liquids (RTILs) are molten salts with low melting points, non-volatility, high ion-conductivity, and high thermal, chemical and radiation stability. The modification of PVDF with RTILs leads to various functional PVDF materials with improved electric and dielectric performance. In this chapter, high performance anti-static PVDF/IL materials, as well as dielectric PVDF/IL materials, are introduced systematically. The former, anti-static PVDF/IL materials, are based on thermodynamically miscible systems, including miscible PVDF/IL films, PVDF/IL composite nanofibrous films and carbon nanotube (CNT)-integrated PVDF/IL nanocomposites (namely, PVDF/IL–CNT composites), which are fabricated by physical methods. In contrast, dielectric PVDF/IL materials are produced by radiation chemical grating of ILs onto the PVDF molecular chains. Furthermore, dielectric PVDF/IL materials with incorporation of carbon black (CB) into the IL-g-PVDF/IL are presented. The structure–property relationships of these two kinds of PVDF/IL-based materials have been discussed systematically.