Enhanced CO2 separation properties by incorporating poly(ethylene glycol)-containing polymeric submicrospheres into polyimide membrane

• PEG-containing submicrosphere was used as novel filler to prepare hybrid membranes.
• CO2 solubility was increased with PEGSS incorporation.
• N2 and CH4 permeabilities were both decreased with PEGSS incorporation.
• CO2/N2 and CO2/CH4 selectivities were both increased in hybrid membranes.

Poly(ethylene glycol)-containing polymeric submicrospheres (PEGSS) were synthesized via distillation precipitation polymerization and incorporated into polyimide (PI) matrix to prepare hybrid membranes. The PEGSS and hybrid membranes were characterized by Fourier transform infrared (FTIR) spectra, transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). Single gas permeabilities of N2, CH4 and CO2 were measured by using the time-lag method. The hybrid membranes showed enhanced CO2 permeability and CO2/N2, CO2/CH4 selectivities at low PEGSS loadings. The favorable affinity between PEGSS and CO2 greatly enhanced CO2 solubility and thus CO2 permeability. Whereas, N2 and CH4 permeabilities both decreased for the tortuous gas transport pathways by PEGSS incorporation. Particularly, PI–PEGSS(20) membrane, with 20 wt% PEGSS loading, showed 35% of increase in CO2 permeability and 104% of increase in CO2/N2 selectivity compared with those of pristine polyimide membrane.