Morphology of block copolymers from neutron scattering

Abstract

Block copolymers are widely used commercially and so a complete understanding of these systems requires that the nature of the polymer interface, the effect of deformation and the interaction between polymer substituents are known. Triblock copolymers of poly(styrene-isoprene-styrene) were synthesised and used in a Small Angle Neutron Scattering (SANS) study of deformation (Ch. 3) . Three sets of samples were made and, of these, two sets were found to have degraded giving unexpected results (Ch. 3.2). The third set, SPH150 series, however, did exhibit the expected anisotropy on deformation (Ch. 3.3). In these samples, the extension parallel to the stretch direction was affine for all elongation ratios studied and, perpendicular to the stretch direction, the extension was non-affine. The interaction between polymer substituents was examined using SANS on an isotopic diblock copolymer of polystyrene to ascertain if the mixing of hydrogenous and deuterated species was ideal (Ch. 4) . The results obtained showed the mixing between these species could be assumed to be ideal. The nature of the polymer-polymer interface was studied on the CRISP reflectometer using poly(styrene- isoprene) diblock samples (Ch. 5) . The results obtained for unannealed samples showed that a 'pseudo- equilibrium' had been achieved in these samples which was lost on annealing.