PEO-based CO2-philic mixed matrix membranes compromising N-rich ultramicroporous polyaminals for superior CO2 capture

Polymer molecular sieve materials (PMS) are promising porous fillers that can be used to fabricate highperformance gas separation mixed matrix membranes (MMMs) to overcome the inherent trade-off. In this work, a nitrogen-rich ultramicroporous (0.34 nm, 0.50 nm) polyaminal network (PAN-NH2) was introduced into crosslinked PEO polymer to prepare CO2-philic MMMs with superior CO2 capture performance. Due to the synergistical interaction of the dipole-quadrupole and molecular sieving effect, PAN-NH2 demonstrates excellent molecular recognition of CO2. PAN-NH2 can be well dispersed in polymer matrix to achieve good polymer-filler interface compatibility. The incorporation of PAN-NH2 significantly improves the CO2 permeability and selectivity of membranes by increasing the CO2 solubility and providing a selective CO2 transport highway. For instance, the CO2 permeability of mixed gas (15% CO2/85% N-2, 50% CO2/50% CH4) permeation tests for 2.0 wt % PAN-NH2/PEO was increased from 340 Barrer (crosslinked PEO) to 1160 Barrer along with CO2/N-2 selectivity of 73.0 and CO2/CH4 selectivity of 19.7, surpassing the Upper bound (2019) and Upper bound (2008), respectively. The long-time stability of PAN-NH2/PEO MMMs is good, which endow them with great potential in practical CO2 capture. In addition, this work demonstrates the potential of functional ultramicroporous PMS in the preparation of high-performance MMMs for other gas separation processes.

Automated summary

This study introduces a nitrogen-rich ultramicroporous polyaminal network (PAN-NH2) into crosslinked PEO polymer to prepare CO2-philic MMMs with superior CO2 capture and transport performance, thanks to the synergistic effect of the dipole-quadrupole interaction and molecular sieving.