Miscibility and interactions in poly(n-propyl methacrylate)/poly(vinyl alcohol) blends

Poly(n-propyl methacrylate) (PPMA) is miscible with poly(vinyl alcohol) (PVA) over the whole composition range as shown by the existence of a single glass transition temperature in each blend. The interaction between PPMA and PVA was examined by Fourier transform infrared spectroscopy and solid-state nuclear magnetic resonance spectroscopy. The interactions mainly involve the hydroxyl groups of PVA and the carbonyl groups of PPMA. The measurements of proton spin-lattice relaxation time reveal that PPMA and PVA do not mix intimately on a scale of 1-3 nm, but are miscible on a scale of 20-30 nm. A small negative interaction parameter value has been obtained by melting point depression measurement.