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

Matrix polymerization can be viewed as an intriguing procedure for the preparation of homogeneous blends that are otherwise difficult or practically impossible to prepare. Poly( p -phenyleneterephthalamide) has been synthesized by direct polycondensation in the presence of poly( N -vinylpyrrolidone) or poly(4-vinylpyridine) as polymer matrices. The molecular weight 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 molecular weight 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 T 1 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.