Synthesis and characterization of poly(ether urethane)‐nylon 6 block copolymer

Abstract poly(ether urethane) (PEU) prepolymer terminated with isocyanate at both ends was prepared by controlling the mol ratio of poly(tetramethylene glycol) and methane diphenyl‐4,4'‐diisocyanate. Using this prepolymer as an activator, the anionic polymerization of ϵ‐ caprolactam was carried out to obtain PEU‐nylon 6 block copolymer. The phase structure of the block copolymers was characterized on the basis of molecular interaction. The results of dynamic mechanical and thermal analyses revealed that the block copolymer films prepared via melt pressing and subsequent quenching had a one‐phase structure. The equilibrium melting temperatures determined by a Hoffman‐Weeks plot showed that the two blocks are miscible in the melt state. N‐Trifluoroacetylation of the block copolymer led to the conclusion that this miscible behavior is due mainly to the specific interaction between urethane groups in PEU block and amide groups in nylon 6 block through hydrogen bonding.