Preparation and characterization of aliphatic polycarbonate membrane for CO2 gas separation application

Abstract

The emission of significant amounts of CO₂ from human industry has caused severe environmental damage, necessitating effective CO₂ capture methods for sustainable development. Membrane technology stands out as one of the most effective and economical solutions. In recent decades, polymer membranes have been recognized for their viability in gas separation applications. Aliphatic polycarbonates (APCs) are particularly notable due to their high chain segment flexibility, degradability, ease of processing, and the presence of carbonate groups, which enhance their affinity for CO₂. This study uses a one-pot melt polycondensation process to synthesize three high-molecular-weight APCs: poly(1,4-butylene carbonate) (PBC), poly(1,5-pentamethylene carbonate) (PPC), and poly(1,6-hexamethylene carbonate) (PHC) from dimethyl carbonate and various diols. To improve the mechanical properties of the APC separation membranes, capping modification was applied. The molecular weights of PBC, PPC, and PHC were 6.48 × 10⁴ g/mol, 4.78 × 10⁴ g/mol, and 5.76 × 10⁴ g/mol, respectively. These membranes were prepared by the evaporative solvent method. The PHC membrane demonstrated a CO₂ permeability of 20.84 Barrer and a CO₂/N₂ selectivity of 22.24 at 35 °C under 0.1 MPa, approaching Robeson’s upper bound and indicating substantial potential for application.