Synthesis of Heteroarm Star-Shaped Block Copolymers with Cyclotriphosphazene Core and Their Compatibilizing Effects on PPO/Nylon 6 Blends

The preparation and compatibilizing ability of heteroarm star-shaped block copolymers (6 and 8) composed of polystyrene and nylon 6 units diverged from the phosphazene core were investigated. The heteroarm star-shaped copolymers were prepared by a partial coupling reaction of the acid chloride of hexakis(4-carboxyphenoxy)cyclotriphosphazene [4, (4-ClCOC6H4O)6N3P3] with polystyrene having a terminal amino group (PSt−NH2) or poly(styryllithium), followed by the ring-opening polymerization of e-caprolactam (e-CL) with the residual carboxyl group in the phosphazene core. The coupling reaction of telechelic PSt−NH2 and poly(styryllthium) with 4 occurs smoothly to give carboxyphenoxycyclotriphosphazenes carrying 2.2−4.7 polystyrene chains, 5 and 7, respectively. The polymerization of e-CL with hexakis(4-carboxyphenoxy)cyclotriphosphazene [2, (4-HOOCC6H4O)6N3P3] showed that all carboxyl groups participate in the initiation of polymerization to give hexaarmed star-shaped polymers. This implies that the residual c...