Microstructural analysis of poly(vinylidene fluoride) using benzene derivative pyrolysis products

Poly(vinylidene fluoride) (PVDF) was pyrolyzed, and the pyrolysis products were analyzed using gas chromatography/mass spectrometry (GC/MS) to develop a method for identification of the microstructures of head-to-tail (H-T), tail-to-tail (T-T), and head-to-head-to-tail-to-tail (H-H-T-T) sequences. Key pyrolysis products to determine the relative degrees of the microstructures were benzene derivatives. 1,4-Difluorobenzene, 1,2,4-trifluorobenzene, and 1,3,5-trifluorobenzene were major pyrolysis products as benzene derivatives. 1,3,5-Trifluorobenzene and 1,2,4-trifluorobenzene were formed from two HF-eliminated PVDF by 1,6-HF elimination and 1,6-rearrangement, while 1,4-difluorobenzene was generated from two HF-eliminated PVDF by 1,6-H₂ elimination and 1,6-rearrangement. 1,3,5-Trifluorobenzene was generated from the H-T sequence, whereas 1,4-difluorobenzene was formed from the T-T one. 1,2,4-Trifluorobenzene can be formed from the H-H-T-T sequence. Relative component ratios of the H-T, T-T, and H-H-T-T sequences of PVDFs can be estimated by comparing relative abundances of the benzene derivative pyrolysis products.