Surface structure of crystallites of VDF/TrFE copolymers

Ultra-thin films of a copolymer of vinylidene fluoride and trifluoroethylene were prepared by spin coating on a substrate that was coated with gold or aluminum by vacuum deposition. Samples were annealed at various temperatures. The surface was observed by using an atomic force microscope. The surface structure was found to depend on the annealing temperature as well as on the film thickness. As the annealing temperature rises up to the melting temperature, the granular structure observed at the surface becomes larger. Once the annealing temperature exceeds the melting temperature, the surface structure drastically changes. By comparing the structure of various samples, the interaction between polymer molecules and the substrate will be discussed.