Effects of amino functionalized polyhedral oligomeric silsesquioxanes on cross-linked poly(ethylene oxide) membranes for highly-efficient CO2 separation

Abstract

In this study, the hybrid cross-linked membranes consisting of amino functionalized polyhedral oligomeric silsesquioxanes (POSS-NH2) nanoparticles and CO2-philic poly(ethylene oxide) (PEO) are prepared via a facile one-step method. Porous POSS-NH2 with abundant amino groups in the polymer matrix generates a compatible interface between the polymer matrix and nanoparticles, enhancing the CO2 permeability. Due to the synergetic effects of nanoporous POSS-NH2 and CO2-philic PEO, the hybrid cross-linked membranes exhibit excellent CO2 permeability and selectivity. A high CO2 permeability of 385.8 Barrer in the hybrid cross-linked membrane is achieved, which is 242% of that of pristine cross-linked membrane. The gas transport performance is explained based on the solution-diffusion mechanism and diffusion coefficient and solubility coefficient are evaluated. Furthermore, thermodynamics is explored to clarify the enhancement of gas transport performance in hybrid cross-linked membranes. The gas permeability of CH4, H2, N2, and CO2 continuously improved with temperatures. The activation energies of CH4, N2, H2 and CO2 in hybrid cross-linked membranes are typically lower than those in the pristine cross-linked membrane, which results in the fast transportation of gases. Our developed membranes have demonstrated a promising prospect for sustainable CO2 separations.