Characterization of the structure of the stereocomplex of poly(methyl methacrylate) in solution from NMR relaxation data

From the values of relaxation times T2 determined on a pulse spectrometer, and from the shape of bands in high resolution (HR‐) and broad line (BL‐) NMR spectra, two types of protons, different in mobility, were found to exist in the associated stereocomplex of isotactic (it‐) and syndiotactic (st‐) poly(methyl methacrylate) (PMMA). From the analysis of NMR spectra, measured at magic angle rotation (MAR‐NMR), the mobility of the ester groups in the stereocomplex is shown to be greatly hindered. Temperature changes of HR‐NMR spectra of mixed solutions of it‐ and st‐PMMA in benzene indicate that the associated segments of the stereocomplex can be characterized as junctions of a network of nonassociated sequences.