PIM-PI-1 and Poly(ethylene glycol)/Poly(propylene glycol)-Based Mechanically Robust Copolyimide Membranes with High CO<sub>2</sub>-Selectivity and an Anti-aging Property: A Joint Experimental–Computational Exploration
Iqubal Hossain, Sanggil Park, Asmaul Husna, Yeonho Kim, Hyungjun Kim, Tae‐Hyun Kim
Abstract
Polymer membranes with excellent thermomechanical properties and good gas separation performance are desirable for efficient CO2 separation. A series of copolyimide membranes are prepared for the first time using PIM-PI-1, a hard segment with high CO2 permeability, and poly(ethylene glycol)/poly(propylene glycol) (PEG/PPG), a soft segment with high CO2 selectivity. Two different unit polymers are combined to compensate the limitations of each polymer (e.g., the fast aging and moderate selectivity of PIM-PI-1 and the poor mechanical properties and lower permeability of PEG/PPG). The corresponding PIM-(durene–PEG/PPG) membranes exhibit an excellent combination of mechanical properties and gas separation performance compared to the typical PI-PEG-based copolymer membrane. The improved mechanical property is attributed to the unique chain threading and the reinforcement between the spiro unit of PIM and the flexible PEG/PPG at the molecular level, which has not previously been exploited for membranes. The PIM-(durene–PEG/PPG) membranes show a high CO2 permeability of 350–669 Barrer and a high CO2/N2 selectivity of 33.5–40.3. The experimental results are further evaluated with theoretical results obtained from molecular simulation studies, and a very good agreement between the experimental results and simulation results is found. Moreover, the PIM-(durene–PEG/PPG) copolymer membranes display excellent anti-aging performance for up to 1 year.