Miscibility in blends of poly (4-vinylpyridine)/poly (4-vinylphenol) as studied by 13C solid-state NMR

The miscibility of poly (4-vinylpyridine) (P4VP) with poly (4-vinylphenol) (PVPh) blends was investigated over a wide range of compositions by differential scanning calorimeter (DSC), Fourier transform infrared spectroscopy (FTIR), and high-resolution solid-state nuclear magnetic resonance (NMR) spectroscopy. DSC results show that the Tgs of the P4VP/PVPh blends are much higher than those of the calculated weight-average values. The proton spin–lattice relaxation times in the laboratory frame, T1(H), and the rotating frame, T1ρ(H), were studied as a function of blend composition. T1(H) and T1ρ(H) results demonstrate that the spin diffusion can completely average out the entire relaxation process. It was also found that the intimate mixing of the polymer blends restricts the local chain mobility.