Effect of homopolymer molecular weight on the morphology of block copolymer/homopolymer blends.
01 January 1987
Small-angle neutron scattering studies have been performed on a series of blends containing hydrogenated butadiene (hPB) homopolymer dispersed in a matrix of styrene-hPB-styrene triblock copolymer. The domain (long) spacing and the thickness of hPB lamellae are greatly affected by the molecular weight of the homopolymer. The hPB lamellae are contracted upon the addition of low molecular weight homopolymer and expanded when longer homopolymer chains are added. These effects can be qualitatively explained as the result of relaxing constant density and increased volume fraction constraints by the distribution of the homopolymer chains.