Solvent effects on the miscibility of PMMA/PVAc blends II. Using two-dimensional NMR method, NOESY

The influence of solvent on the miscibility of poly(methyl methacrylate)/poly(vinyl acetate), PMMA/PVAc, and the interpolymer interactions responsible for their miscibility were investigated. 2D nuclear overhauser effect spectroscopy, NOESY, experiments were performed with pure polymers and also with 50/50 blend. Under conditions of blend miscibility, chloroform at 40 degrees C and toluene at 30 degrees C, NOESY results indicated the presence of two different types of intermolecular interactions between (i) methoxy protons of PMMA and methyne protons of PVAc; (ii) methoxy protons of PMMA and methyl protons of PVAc. In immiscible conditions, in DMF and in benzene, both at 40 degrees C, only type (ii) interactions were detected. These results indicate that intermolecular interactions between the methoxy protons of PMMA and the methyne protons of PVAc are responsible for the miscibility of the blends in chloroform and toluene. The interactions between the methoxy protons of PMMA and the methyl protons of PVAc do not contribute to the miscibility of the blend and were explained as originating from contacts of unlike polymers in the interphase. (C) 1999 Elsevier Science Ltd. All rights reserved.