Study of molecular interfaces in polymer thin-film composite membranes for the efficient gas separations

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This work is devoted to developing and investigating thin-film composite (TFC) membranes with selective molecularly-thin interfaces between polymers to achieve efficient carbon dioxide (CO2) separation from complex mixtures with other gases. During the first year, the research is progressing according to the original plan. The focus was to investigate how the surface modification of the hydrophobic polymer layer by water vapor-generated plasma influences the formation of the selective interface with the hydrophilic selective layer. It was found that some minimum critical amount of surface modification is essential to form the proper laminate structure. Furthermore, the influence of surface modification by the plasma treatment alone was found insufficient to increase the membrane's selectivity towards CO2.The gas transport of CO2, O2, and N2 was thoroughly studied. The existence of the molecular interface was found to be the essential factor in the highly selective CO2/N2 and CO2/O2 separation. With the inclusion of the selective interface in the structure of the TFC, the selectivity increased to about 35 and 13 for CO2/N2 and CO2/O2 separation, respectively (~10 and ~5 in the membranes without the selective layer and interface). Finally, this work focuses on their membrane application for the direct air capture of CO2. Direct air capture is an important technology to mitigate the effects of climate change. By capturing carbon dioxide directly from the air, we can reduce the amount of greenhouse gases in the atmosphere and slow down the rate of global warming.