Phase stability in pressure-responsive block copolymer/homopolymer blends

Blending pressure-responsive block copolymers (BCPs) with conventional polymers enables energy-efficient, low-temperature processing through phase transitions induced by pressurization. However, the pressure-responsive phase behavior of BCP/homopolymer blends remains poorly understood. Here, the compressible random-phase approximation theory is extended to BCP/homopolymer blends to construct pressure–composition spinodal phase diagrams. The results reveal that macrophase and microphase separation, as well as the associated transition pressures, are governed by key molecular parameters: the chain-length ratio of homopolymers to BCPs, the absolute chain lengths, and the block ratio. This study provides a theoretical framework for pressure-induced phase transitions in BCP/homopolymer blends, with important implications for the rational design of pressure-responsive polymers with tailored low-temperature processability.