About the microstructure of PCVD prepared crystal mats of statistical oligo-vinylidene-fluoride-trifluoroethylene in relation to other fluorinated polymers

The room temperature phase of the physical/chemical vapor‐deposited statistical co‐oligomer VDF/TrFE(70/30) has been characterized by different experimental methods such as small‐angle x‐ray scattering, wide‐angle x‐ray diffraction, size‐exclusion chromatography, infrared absorption and optical refractometry. The characterization of the elastic properties was carried out using high‐performance Brillouin spectroscopy in connection with special scattering geometries. The co‐oligomer VDF/TrFE(70/30) was obtained by cracking the parent statistical copolymer and subsequently vapor depositing the shortened chains on highly oriented PTFE substrates (PIA‐technique). The room temperature phase of the resulting oriented waxy crystal mats of VDF/TrFE(70/30) is predominantly ferroelectric. The physical properties are very different to those of similarly PIA‐prepared n‐alkanes, perfluoroalkanes, and blockfluoroalkanes. The microstructure of VDF/TrFE(70/30) is interpreted in terms of partially crystalline nano‐sized structures giving rise to a marked freezing process below room temperature. © 1995 John wiley & Sons, Inc.