Cosolvent-regulated time–composition rheological equivalence in block copolymer solutions

Abstract

The morphological and mechanical attributes of triblock copolymer solutions composed of miscible, midblock-selective solvents are investigated by small-angle scattering and dynamic rheology. Variation in cosolvent composition at constant copolymer concentration has little effect on copolymer morphology, but promotes large differences in matrix relaxation, as evinced by changes in the shape of isothermal frequency spectra. Shifting these spectra in the frequency domain reveals the existence of time–composition equivalence, wherein shift factors scale with the viscosity of the cosolvent mixture.