IDENTIFICATION OF INTERMOLECULAR INTERACTIONS IN 1,2-POLYBUTADIENE/POLYISOPRENE BLENDS

The intermolecular interactions responsible for miscibility in 1,2-polybutadiene/cis polyisoprene blends have been investigated using solid-state two-dimensional (2D) NMR. We find that high- resolution proton spectra can be obtained at temperatures above T-g using magic-angle spinning and that intermolecular association can be probed using nuclear Overhauser effect spectroscopy. The results reveal the existence of weak intermolecular interactions between the polyisoprene methyl group and the 1,2-polybutadiene vinyl side chain. These studies demonstrate the large effect that weak intermolecular interactions can have on the phase structure of polymer blends.