SOLID-STATE C-13-NMR STUDIES OF THE AGING OF POLY(VINYLIDENE FLUORIDE) POLY(METHYL METHACRYLATE) BLENDS

Solid state 13C‐NMR was used to investigate the miscibility and subsequent separation of solution‐cast blends of poly(vinylidene fluoride) (PVF2) and poly(methyl methacrylate) (PMMA) with aging for a range of compositions. It was found that one amorphous phase and intimate mixing of the polymer chains in this phase existed for all compositions of the blends, even after 2 months of aging at room temperature as determined by the proton spin lattice relaxation time T1ρH in the rotating frame, and the time constant TCH for transfer of magnetization. The T1ρH is sensitive to the spatial homogeneity of the blend via spin diffusion and would indicate the presence of phases or domains in the amorphous component of the blend larger than approximately 19 Å. The TCH is proportional to the inverse sixth power of the interatomic distances needed for transfer of magnetization from proton to carbon and would be sensitive to a separation of polymer chains in the amorphous phase with aging on the order of 4–5 Å. There was an increase of the T1ρH and TCH values with aging, indicating that a subtle separation between unlike chains in the amorphous phase was occurring although a single amorphous phase was present. Copyright © 1990 John Wiley & Sons, Inc.