High-Resolution Carbon-13 Nuclear Magnetic Resonance Studies of Polymers in the Solid State. Aromatic Polyesters

High-resolution 13C NMR spectra have been obtained for the insoluble, highly crystalline homopolymer of p-hydroxybenzoic acid, two methoxy derivatives of this polymer, and two copolymers with biphenylene terephthalate by use of proton dipolar decoupling, magic-angle spinning, and 13C crosspolarization techniques. Resolution is sufficient that the majority of carbons in the homopolymer repeat units appear as individual resonance lines. The widths of resonance lines (⪕15Hz) are 3-6 times more narrow than those obtained for glassy polymers—a result which is attributed to both the rigidity of these aromatic polyesters and the homogeneous local environment associated with crystal habit. © 1979, American Chemical Society. All rights reserved.