Distribution of Chain Ends Inside the Polybutadiene Microspheres of SB Diblock Copolymers

摘要

Two polystyrene polybutadiene block copolymers were examined in small angle neutron scattering (SANS) experiments designed to probe the location of the polybutadiene chain ends inside the polybutadiene microspheres of these specimens. One of the copolymers, SBm, was phase-matched; the B moiety was synthesized using a suitable mixture of deutero and normal butadiene monomer. The other copolymer, SBmBd, contained short perdeuterated polybutadiene sequences at the end of the polybutadiene block of each of the molecules. Consideration of scattering intensities and the form of the scattering pattern exhibited by SBmBd indicated that the Bd chain ends are essentially uniformly distributed throughout the volume of the spheres. A model in which the Bd ends cluster at the core of the spheres failed to reproduce the essential features of the observed SANS pattern.