On the synthesis of poly(p-benzamide) block copolymers by the phosphorylation reaction

Abstract The multistep method suggested in the literature for the synthesis of poly( p -benzamide) (PBA) block copolymers has been critically re-examined. The reaction products after each step have been isolated and characterized, and the extent of competitive processes evaluated. Under the chosen experimental conditions, almost no PBA copolymer is formed in the presence of terephthalic acid and p -aminobenzhydrazide. The increase of the limiting viscosity number has been attributed to coupling reactions between PBA chains by the difunctional reagents used in steps 2 and 3.