The authors gratefully acknowledge the fundings from the Strategic Project of CIEPQPF
(UIDB/00102/2020), CICECO-Aveiro Institute of Materials (UIDB/50011/2020, UIDP/50011/2020 &
LA/P/0006/2020), CIMO (UIDB/00690/2020 and UIDP/00690/2020) and SusTEC (LA/P/0007/2021),
financed by Fundação para a Ciência e Tecnologia (FCT) through national funds. J. S. Cardoso is also
grateful for the financial support of the FCT through the PhD grant (SFRH/BD/148170/2019).
The use of ionic liquid [emim][Tf2N] as an additive in polyethersulphone (PES) and nanosized silico-aluminophosphate-34 (SAPO-34) mixed matrix membrane was studied through the incorporation of different amounts of [emim][Tf2N] in the membrane composition, as presented in this work, varying from 10 to 40 wt%. Through gas permeation tests using CO2 andN2, the membrane composition containing 20 wt% [emim][Tf2N] led to the highest increase in CO2 permeability and CO2/N2 selectivity. The use of low concentrations of additive (10–20 wt%) promoted a state called antiplasticization; in this state, the permeability was even more regulated by the kinetic diameter of the species which, in this work, permitted achieving a higher CO2/N2 selectivity while increasing the CO2 permeability until an optimal condition. [emim][Tf2N] also promoted a better dispersion of SAPO-34 particles and an increase in the flexibility of the polymeric matrix when compared to a film with the same composition without [emim][Tf2N]. Moreover, the characterizations corroborated that the inclusion of [emim][Tf2N] increased the zeolite dispersion and improved the polymer/zeolite compatibility and membrane flexibility, characterized by a decrease in glass transition temperature, which helped in the fabrication process while presenting a similar thermal resistance and hydrophilicity as neat PES membrane, without affecting the membrane structure, as indicated by FTIR and a contact angle analysis.
