2-DIMENSIONAL NMR-STUDIES OF INTERMOLECULAR INTERACTIONS IN POLY(VINYL CHLORIDE) POLY(METHYL METHACRYLATE) MIXTURES

Two-dimensional nuclear Overhauser effect spectroscopy (2D NOESY) is used to study intermolecular interactions in concentrated mixtures of poly(methyl methacrylate) (PMMA) and poly(vinyl chloride) (PVC), a polymer mixture capable of forming compatible blends. Cross peaks in the 2D NOESY spectra that result from internuclear separations of less than 5 angstrom are observed between PMMA and PVC for polymer concentrations greater than 25 wt %. The intermolecular cross peaks do not depend on PMMA or PVC tacticity, but decrease with increasing temperature, and the intermolecular complex is disrupted by trace amounts of water. The distances measured from a quantitative analysis of the NOESY spectra as a function of temperature show that the PMMA has a preferred conformation, and that the intermolecular complex has a defined geometry. Determination of the interaction mechanism and geometry from structural studies is the first step toward the molecular design of new compatible blends.