Effect of Cross-linking on the Structure and Thermodynamics of Lamellar Block Copolymers

The effect of cross-linking on the structure and thermodynamics of a lamellar poly(styrene-\textit{block}-isoprene) copolymer was studied using small angle X-ray scattering (SAXS), depolarized light scattering (DPLS) and transmission electron microscopy (TEM). The selective cross-linking of the polyisoprene block took place either in the disordered state, in an isotropic ordered state, or in a shear-aligned ordered state. Using DPLS and TEM, the grain structure as a function of cross-linking density was studied. The order-disorder transition temperature for various block copolymer networks was determined as function of cross-linking density, and comparisons are made to a mean-field theory.