Architecture-Engineered Semi-Crystalline Microporous Polymer Membranes for Precise Molecular Separation

Amorphous polymer membranes typically suffer from low fractional free volume (FFV) due to structural flexibility, limiting separation performance and operational stability. Herein, we propose a strategy that constrains segmental motion by π-π-driven ordered stacking. Guided by Random Forest (RF) analysis of substructure marginal contributions, we selected a pre-existing high FFV aromatic substructure (p-terphenyl) and, inspired by articular joints, assembled it into rigid π-π-stacked domains linked by flexible amide units, creating a semi-crystalline membrane (DATP) characterized by short-range order embedded within long-range disorder. Organic-organic interfacial polymerization (OOIP) yields this scalable network, further reducing transport resistance by tuning ordered and disordered domain arrangements. The DATP membrane features rigidly interconnected channels, increasing FFV by 14% to 35.5% compared to the amorphous membrane (DAB), while reducing interconnected volume loss during operation by 14.3%. This achieves a record-high methanol permeability of 2779 L m^-2 h^-1 bar^-1 nm and the highest selectivity among all polymer membranes with comparable molecular weight cut-off (MWCO). Extended to active pharmaceutical ingredients (APIs) separation, it enables 50-fold enrichment within 2.5 h and shows 28% higher selectivity than commercial membranes. By endowing polymer membranes with the structural tunability of crystalline materials, this work combines well-defined pore architecture with scalable fabrication.