19F- and 1H-NMR spectra of tetrafluoroethylene–propylene copolymers

Abstract

High resolution 94-MHz 19F- and 100-MHz 1H-NMR spectra were measured on a series of tetrafluoroethylene (TFE)-propylene (P) copolymers having a range of composition (TFE/P molar ratio = 37/63–55/45) and polymerized at different temperatures (−23, 25 and 65°C). The spectra were analyzed in relation to copolymer compositions. The assignment of 19F resonance in terms of tetrads proposed previously was confirmed, and the tentative assignment of 1H resonances was proposed in terms of triads. The spectra thus interpreted revealed the sequence distribution of the copolymers. Copolymer compositions calculated from NMR spectra and elemental analysis agreed rather well with each other. Monomer reactivity ratios were calculated from the sequence distributions and compared with those obtained from the elemental analysis. It was observed that highly alternating copolymers are obtained in this system over a wide range of monomer composition at lower temperatures and that a deviation from alternancy increases slightly with rising polymerization temperature.