(663c) Structure and Gas Transport Characteristics of Triethylene Oxide-Grafted Polystyrene-B-Poly(ethylene-co-butylene)-B-Polystyrene (SEBS)
AIChE Annual Meeting
Friday, November 20, 2020 - 8:15am to 8:30am
Microphase-separated block polymers have emerged as an interesting material platform for membrane applications, such as gas separation, water purification, proton-exchange membranes, anion-exchange membranes, and polymer electrolytes for battery applications. In these multi-phase systems, one of the phases is continuous and governs the transport of small molecules such as gas, water, and ions, while another phase provides mechanical property support. In this work, SEBS block copolymer is used as a polymer matrix to incorporate triethylene oxide (TEO) functionality. The short ethylene oxide segment is chosen to avoid crystallization, which is confirmed by DSC and wide-angle X-ray scattering. The gas permeability results reveal that CO2/N2 selectivity increased with increasing incorporation of TEO functional group. The highest CO2 permeability (281 Barrer) and CO2/N2 selectivity was obtained for the membrane with the highest TEO incorporation (57 mol%). Increasing the TEO content in these copolymers results in an increase in CO2 solubility and a decrease in C2H6 solubility. For example, as the grafted TEO content increased from 0 to 57 mol%, the CO2 solubility and CO2/C2H6 solubility selectivity increased from 0.72 to 1.3 cm3(STD)/cm3 atm and 0.47 to 1.3 at 35°C, respectively. The polar ether linkage in TEO-grafted SEBS copolymers exhibits favorable interaction with CO2 and non-favorable interaction with nonpolar C2H6, enhancing CO2/C2H6 solubility selectivity. This work demonstrates an effective way of designing polymers with multi-functions with excellent separation performance, mechanical properties, and processability.