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)/po ly(vinyl acetate), PMMA/PVAc, and the interpolymer interactions responsible for their miscibility were investigated. 2D nuclear overhauser effect spec troscopy, NOESY, experiments were performed with pure polymers and also wit h 50/50 blend. Under conditions of blend miscibility, chloroform at 40 degr ees C and toluene at 30 degrees C, NOESY results indicated the presence of two different types of intermolecular interactions between (i) methoxy prot ons of PMMA and methyne protons of PVAc; (ii) methoxy protons of PMMA and m ethyl protons of PVAc. In immiscible conditions, in DMF and in benzene, bot h at 40 degrees C, only type (ii) interactions were detected. These results indicate that intermolecular interactions between the methoxy protons of P MMA 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 mis cibility of the blend and were explained as originating from contacts of un like polymers in the interphase. (C) 1999 Elsevier Science Ltd. All rights reserved.