Solid‐state 1 H → 19 F/ 19 F → 1 H CP/MAS NMR study of poly(vinylidene fluoride)

Solid‐state 1 H → 19 F and 19 F → 1 H cross‐polarization magic angle spinning (CP/MAS) NMR spectra have been investigated for a semicrystalline fluoropolymer, namely poly(vinylidene fluoride) (PVDF). The 1 H → 19 F CP/MAS spectra can be fitted by five Lorentzian functions, and the amorphous peaks were selectively observed by the DIVAM CP pulse sequences. Solid‐state spin‐lock experiments showed significant differences in T 1ρ F and T 1ρ H between the crystalline and amorphous domains, and the effective time constants, T HF * and T 1ρ *, which were estimated from the 1 H → 19 F CP curves, also clarify the difference in the strengths of dipolar interactions. Heteronuclear dipolar oscillation behaviour is observed in both standard CP and 1 H → 19 F inversion recovery CP (IRCP) experiments. The inverse 19 F → 1 H CP‐MAS and 1 H → 19 F CP‐drain MAS experiments gave complementary information to the standard 1 H → 19 F CP/MAS spectra in a manner reported in our previous papers for other fluoropolymers. The value of N F / N H (where N is a spin density) estimated from the CP‐drain curve is within experimental error equal to unity, which is consistent with the chemical structure. Copyright © 2001 John Wiley & Sons, Ltd.