Abstract

The phase behavior of six poly(styrene-b-isoprene) (SI) diblock copolymers has been mapped out in the styrene-selective solvents di-n-butyl phthalate (DBP), diethyl phthalate (DEP), and dimethyl phthalate (DMP). The polymer molecular weights were chosen to make the melt order−disorder transition (ODT) experimentally accessible, and the styrene compositions f ranged from 0.23 to 0.70, to access the full range of melt morphologies. For each polymer a phase diagram was constructed, with polymer volume fractions, φ, ranging from 0.01 to 1.0 and temperatures, T, from 0 to 250 °C. Phase assignments were based on small-angle X-ray scattering (SAXS), and the ODTs and order−order transitions (OOTs) were located by a combination of SAXS, rheology, and static birefringence. The critical micelle temperatures (cmt) in dilute solution were determined by dynamic light scattering. In this manner the full “phase cube” was mapped out in each solvent, enabling generation of phase maps (φ,f) at constant T and (f,T) at consta...

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