Investigation on the Phase Diagram and Interaction Parameter of Poly(styrene-b-1,3-cyclohexadiene) Diblock Copolymers

Abstract

A series of linear diblock copolymers containing polystyrene (PS) and poly(1,3- cyclohexadiene) (PCHD) with high 1,4-microstructure (>87%) were synthesized. Microphase separation in the bulk was examined with transmission electron microscopy (TEM) and smallangle x-ray scattering (SAXS) and compared to computational analysis of the predicted morphological phase diagram for this system. Due to the high conformational asymmetry between PS and PCHD, these materials self-assemble into typical and atypical morphologies expected for linear diblock copolymer systems. Rheological measurements were conducted and revealed order-disorder transition temperatures (TODT) for the first time for PS-b-PCHD copolymers resulting in a working expression for the effective interaction parameter χeff = 32/T – 0.016. Furthermore, we performed computational studies that coincide with the experimental results. These copolymers exhibit well-ordered structures even at high temperatures (~260 0C) providing therefore a better insight concerning their microphase separation in the nanoscale and leading to their potential use as materials in nanotechnology and/or nanolithography applications.