An Investigation on Gas Transport Properties of Cross-Linked Poly(ethylene glycol diacrylate) (XLPEGDA) and XLPEGDA/TiO₂ Membranes with a Focus on CO₂ Separation

Poly(ethylene oxide) (PEO)-based membranes are known as outstanding candidates for carbon dioxide (CO₂) separation as the major greenhouse gas responsible for global warming. In this paper, gas transport properties (solubility, permeability, and diffusivity) of neat and nanocomposite cross-linked poly(ethylene glycol diacrylate) (XLPEGDA) membranes were investigated for CO₂ as well as CH₄, C₂H₄, C₂H₆, C₃H₈, H₂, and N₂ gases. XLPEGDA as a low-molecular-weight PEO, has not been studied much, compared to other PEO-based membranes such as poly(ether-block-amide) (PEBA) for CO₂ capture. To make the conducted research more practical, the operating conditions were selected near to industrial operational conditions, i.e., in the temperature range of 35-75 °C and at pressures up to 16 bar. All membranes were synthesized by UV photopolymerization. To prepare nanocomposite membranes, inorganic titanium dioxide (TiO₂) nanoparticles were incorporated within the polymeric matrix prior to its cross-linking. Structural properties of the prepared membranes were characterized by scanning electron microscopy energy-dispersive X-ray (SEM-EDX), Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), and density analysis. DSC and FTIR results confirmed completeness of the cross-linking reaction. SEM images showed homogeneous structure of the membranes and rather uniform dispersion of the TiO₂ nanoparticles. It was found that incorporation of the TiO₂ nanoparticles, more specifically at 3 wt % loading, results in enhancement of CO₂ permeability and solubility by 39% and 18.5%, respectively. Furthermore, CO₂ selectivity values over the investigated light gases including H₂, CH₄, and N₂ increased by 16.2%, 15.6%, and 26.6%, respectively.