Nylon 6–polyisobutylene sequential copolymers. II. Synthesis, characterization, and morphology of di‐, tri‐, and radial block copolymers

Abstract

Abstract Nylon 6–PIB diblock, triblock, and tristar radial block copolymers have been synthesized from telechelic hydroxyl‐terminated polyisobutylene, PIB(OH) n ( n = 1,2,3), by conversion of this prepolymer with hexamethylene diisocyanate (HMDI), toluene diisocyanate (TDI), N ‐chlorocarbonyl diisocyanate (NCCI), and oxalyl chloride (OxCl) and using the resulting materials as macroactivators for anionic caprolactam polymerization. Prepolymers with molecular weights from 6000 to 38,000 have been employed. Derivatization with NCCI and subsequent anionic caprolactam polymerization gave highest yields and blocking efficiencies. The block copolymers have been characterized by molecular weight and composition. In addition to the expected T g and T m characteristics of long PIB and nylon 6 segments, DSC studies showed an intermediate glass transition at ca. −20°C. Transmission electron microscopy of di‐, tri‐, and radial blocks show increasing segregation and orientation of rubbery/crystalline domains. Tensile strengths and elongations of the block copolymers range from 16.5 to 41 MPa and 15 to 30%, respectively, and stress‐strain diagrams show the effect of block architecture on these properties.