Dioxybiphenyl and chiral dioxybinaphthyl polyphosphazene random copolymers carrying carboxylic acids and their reactions with ∈-caprolactam to form nylon-6-branched phosphazene materials

The phosphazene polymers carrying phenoxycarboxylic acids {[NP(O-C 6H 4-CO 2H) 2] x[NP-(O 2C 12H 8)] 1-x} n [x = 0.2 (1a), 0.35 (1b), 0.5 (1c), 0.7 (1d), 0.85 (1e), x = 1(2)] and the chiral analogues {[NP(O-C 6H 4-CO 2H) 2] x[NP(O 2C 20H 12)] 1-x} n [x = 0.2 (3a), 0.45 (3b), 0.7 (3c)] (O 2C 12H 8 = 2,2'-dioxybiphenyl, O 2C 12H 12 = R-2,2′dioxy-1,1′-binaphthyl) have been synthesized by hydrolysis of the corresponding precursors with [NP(O-C 6H 4-CO 3Pr) 2] units. The new polymers have extensive H-bonding between the -COOH groups in the solid state, and those with x > 0.5 are very soluble in aqueous 0.5 M sodium carbonate. These polymers were used as initiators of the ring-opening polymerization of the ∈-caprolactam (∈-CL) at 230°C to give un-cross-linked polyphosphazenes, branched with short polyamide chains but having a fraction of the phosphazene units (from 20 to 35%) modified by secondary reactions. © 2005 American Chemical Society