TAILORED RIGID-FLEXIBLE BLOCK-COPOLYMERS .1. SYNTHESIS OF DIBLOCKS OFPOLY(P-BENZAMIDE) AND POLY(M-PHENYLENE ISOPHTHALAMIDE)

Anilino-terminated poly(m-phenylene isophthalamide) [PhNH(MPD-I)] and benzoyl terminated poly(p-benzamide) [PhCO(PBA)] were coupled accordin g to a one-pot two-step scheme of Yamazaki's reaction. Diblock copolym ers with varying length of the flexible PhNH(MPD-I) segment, and simil ar length of the rigid PhCO(PBA) block, were freed from unbound homopo lymers exploiting their selective solubility in N,N-dimethyl-acetamide (DMAc) containing varying amounts of LiCl. The method should also all ow a fractionation of the compositional distribution of the copolymers . Copolymers were characterized by H-1 NMR spectroscopy, thermal analy sis and intrinsic viscosity. In an aggregating solvent the viscosity a ppears to decrease with the length of the flexible block.