Pure β -phase formation in polyvinylidene fluoride (PVDF)-carbon nanotube composites

Polyvinylidene fluoride (PVDF) and its copolymers with a particular semi-crystalline conformation ( β ) have evolved as lead (Pb)-free alternatives to electroactive perovskite piezo-, pyro-, and ferroelectric materials. In particular, semi-crystalline ferroelectric polymers are suitable for a large variety of flexible devices and have attracted tremendous research interest. Realizing the application potential of this polar form, there have been numerous attempts to enhance and stabilize this β crystalline phase. A completely pure (100%) β crystalline phase has been achieved in a nanocomposite of PVDF with carbon nanotubes (CNTs) with proper functionalization. With an emphasis on pure ferroelectric β -phase formation and related issues, this paper presents a timely review of the literature on recent sequential development and understanding of PVDF-CNT composites.