Local Glass Transition Temperature () Within Polystyrene Is Strongly Impacted by the Modulus of the Neighboring PDMS Domain.

Profiles in the local glass transition temperature () within polystyrene (PS) next to polydimethylsiloxane (PDMS) domains were determined using a localized fluorescence method. By changing the base to cross-linker ratio, we varied the cross-link density and, hence, the Young's modulus of PDMS (Sylgard 184). The local () in PS at a distance of = 50 nm away from the PS/PDMS interface was found to shift by 40 K as the PDMS modulus was varied from 0.9 to 2.6 MPa, demonstrating a strong sensitivity of this phenomenon to the rigidity of the neighboring domain. The extent the () perturbation persists away from the PS/PDMS interface, ≈ 65-90 nm before bulk is recovered, is much shorter for this strongly immiscible system compared with the weakly immiscible systems studied previously, which we attribute to a smaller interfacial width, as the χ parameter for PS/PDMS is an order of magnitude larger.