Planetary cross-linked structure design of hybrid organosilica membrane by amine-driven polymerization for CO2 separation

Abstract

A hybrid organosilica membrane, with a unique 3-dimensional planetary crosslinked network was fabricated for investigating the effect of in-situ crosslinked network synthesis on the membrane structure. Herein, a dual reaction approach was introduced for the copolymerization. 3-Aminopropyltriethoxysilane (APTES) consisting of amide acts as a shell covering the core cage polyhedral oligomeric silsesquioxane (POSS). Epoxy POSS was selected to construct a tough and 3D free volume as the host for organosilica, to promote gas transport and facilitate a mild reaction with the amide functional group, through the ring-open polymerization without a catalyst. As a branched-chain modified unit, APTES can increase the crosslink density to form the final structure such as a planetary orbit. As a result, it was confirmed that the as-prepared M-0.1A1P(a) formed a planetary structure, from the Si–C main structure surrounded by N using FE-TEM. Moreover, M-0.1A1P(a) showed a maximum selectivity of 77.71 towards CO2/N2, 93.79 towards CO2/CH4, 121.32 towards H2/N2, and 144.86 towards H2/CH4, and an adequate hydrogen permeance of 1.41 × 10−8 mol/(m2sPa) at around 25 °C, confirming that this type of cross-linked network has full potential for the application of small molecular gas separation, especially for CO2.