Development of piezoelectric polymer composites on the basis of poly(vinylidene fluoride)

Poly(vinylidene fluoride) (PVDF) does not only show excellent chemical and thermal stability, it is also unique with respect to ferro-, pyro- and piezoelectric properties. The latter require the occurrence of the β crystalline phase, which is, however, not obtained from PVDF synthesis. Generally, the β crystalline phase is formed in further processing steps such as application of high pressure or drawing and stretching. Upon covalently binding PVDF to carbon nanoobjects (nanoparticles or nanotubes) the β crystalline form is obtained spontaneously. Moreover, self organization of block copolymer during film formation leads to the PVDF domains with β crystallinity. To allow for introduction of the PVDF composites into multi-phase systems it is desirable that the β crystalline phase is retained after temperature treatment. Within the project PVDF properties will be varied systematically and the influence on the crystallinity will be investigated. With respect to incorporation of block copolymers into multi-phase systems the choice of the comonomers and thus the compatibility with the matrix material is of utmost importance. Further, the ratio of block lengths is decisive for the formation of domains and its size. The focus of the project is on the synthesis and characterization of PVDF composites.