Poly(p-phenyleneterephthalamide)-Based Nanocomposites Obtained by Matrix Polycondensation. Synthesis and Solid-State NMR Characterization

Matrix polymn. can be viewed as an intriguing procedure for the prepn. of homogeneous blends that are otherwise difficult or practically impossible to prep. Poly(p-phenyleneterephthalamide) has been synthesized by direct polycondensation in the presence of poly(N-vinylpyrrolidone) or poly(4-vinylpyridine) as polymer matrixes. The mol. wt. effect of the latter polymers on the intrinsic viscosity of the aramid has been investigated. Poly(p-phenyleneterephthalamide), characterized by intrinsic viscosity as high as 14.2 dL/g, is obtained when high mol. wt. poly(N-vinylpyrrolidone) is used. The intimate composites formed in situ have been characterized by solid-state NMR. The parent and daughter polymers in the composite present the same proton T1 relaxation times in the rotating frame, and this value differs from that of the neat polymers; this result demonstrates the intimacy of the blend at the level of a few nanometers.