Infrared spectroscopic studies on crystallization and Curie transition behavior of ultrathin films of P(VDF/TrFE) (72/28)

The structural phase transition of spin-cast vinylidene fluoride (72 mol%)–trifluoroethylene (28 mol%) random copolymer annealed at different temperatures with varying degree of crystallinity was analyzed qualitatively and quantitatively using Fourier transform infrared transmission (FTIR-TS) and grazing incident reflection absorption (FTIR-GIRAS) spectral data. Using factor analysis of the mixture spectra from samples annealed at different temperatures, we have isolated the pure crystalline and pure amorphous-phase spectra, and the crystalline-phase content was determined quantitatively as a function of annealing temperature. A significant increase in the degree of crystallinity was found for samples annealed at Curie transition range. We have also analyzed the spectra obtained at varying temperatures during a heating–cooling cycle and using factor analysis, the pure spectra of the isolated low-temperature and high-temperature phases were obtained. The low-temperature phase spectra appeared similar to that of the isolated crystalline phase.