Baroplastic diblock copolymers exhibit order–disorder transitions and melt upon compression at low temperatures, in some cases even at ambient temperatures. Their unique low-temperature processability makes them promising candidates for sustainable polymeric materials. Despite their potential, however, the molecular mechanisms governing the pressure-induced phase transitions of these copolymers remain largely unexplored. This study develops a compressible self-consistent field theory for baroplastic copolymers based on a simple lattice vacancy model that explicitly incorporates voids to account for compressibility. The theory shows that the selective presence of voids in compressible domains stabilizes the ordered phase, while a reduction of voids under compression leads to the order–disorder transition. In addition, this work demonstrates for the first time the critical role of gas absorption rates in each segment in the pressure-induced order–disorder transition of baroplastic diblock copolymers. These findings have significant implications for the rational design of baroplastic polymers with tailored low-temperature processability.

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晶格空位在压塑性二嵌段共聚物压力诱导相变中的关键作用

压塑性二嵌段共聚物表现出有序-无序转变，并在低温压缩时熔化，在某些情况下甚至在环境温度下。它们独特的低温加工性能使它们成为可持续聚合物材料的有希望的候选者。然而，尽管它们具有潜力，但控制这些共聚物压力诱导相变的分子机制在很大程度上仍未被探索。这项研究基于简单的晶格空位模型，开发了一种压塑性共聚物的可压缩自洽场论，该模型明确地结合了空隙来解释可压缩性。该理论表明，可压缩域中空隙的选择性存在稳定了有序相，而压缩下空隙的减少导致了有序-无序转变。此外，这项工作首次证明了压力诱导的压力塑性二嵌段共聚物的有序-无序转变中每个片段的气体吸收率的关键作用。这些发现对于合理设计具有定制低温加工性能的压塑性聚合物具有重要意义。