Synthesis and CO2 separation of novel polyurethane membranes containing urea linkages

ABSTRACT We synthesized novel polyurethane (PU) membranes from isophorone diisocyanate (IPDI), poly(ethylene glycol) (PEG) with a molecular weight of 2000, aminopropyl‐terminated poly(dimethyl siloxane) (PDMS) with a molecular weight of 2000, and 1,4‐butanediol (BDO) via a two‐step polymerization. The structure of each synthesized membrane was studied through Fourier transform infrared spectroscopy and gel permeation chromatography. The effect of the thermal behavior was determined by differential scanning calorimetry and thermogravimetric analysis. The gas‐permeability characteristics of the PU membranes were then tested for a single gas. The results show that the permeability of CO2 (PCO2) gradually increased with PDMS content. Among these PU membranes, PU‐d (PEG/PDMS = 1:1, PEG/PDMS/IPDI/BDO = 1:3:2) showed the best PCO2 (132.6 Barrer) at 25°C and 1 bar pressure. The gas‐permeability coefficients of each PU membrane at different operating temperatures were investigated, and the results show that PCO2 reached 302.6 Barrer at 65°C and 1 bar. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47723. PU membranes with different urea linkages content were prepared to study CO2 gas permeability. In order to improve the permeability of CO2, urea and PDMS were introduced into PU. It was found that the CO2 permeability of membrane containing urea linkage contents was 139% higher than that of membrane without urea linkage contents, reaching 253.8 Barrer at 65°C.