Bioinspired membrane design, synthesis, and characterization to control microstructure and enable efficient molecular separations

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2021-05

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Abstract

Natural resources are limited, and the failure to capture, store, and re-supply such resources can cause global economic, political, and humanitarian crises such as water scarcity. To mitigate these global risks, membrane separations have been an attractive technology due to their energy efficient and environment-friendly nature compared to other separation technologies such as distillation or chromatography. However, the development of new membranes with good separation properties and processability have been an ongoing challenge. One example is biomimetic membranes. Due to the unexpectedly fast transport and selective separation performances observed in nature, biological membrane components have been attempted for integration into scalable membranes. But maintaining the coherence of their nanoscale transport property at practice-relevant scales have been critically challenging. Bioinspired synthetic membranes have emerged as a good alternative to help resolve these roadblocks faced by biomimetic membranes. Molecular designs of synthetic membranes components enable precise control of microstructures and improve the nanoscale homogeneity of the membranes, both of which are critical for improving membrane separation properties, while increasing reproducibility, cost-efficiency, and processability of the membranes. This dissertation research aims to provide scientific details needed for the developments of bioinspired membranes, spanning the broad considerations from nano- to macroscopic perspectives. First, a new type of artificial water channels (AWCs) is presented as a transport element of bioinspired membranes. A new water permeation mechanism, water-wire networks formed by these AWCs, was shown to achieve fast and selective water transport that exceeds current polymer membranes’ permeability-selectivity limit. Next, a strategy of integrating such bioinspired membrane components, AWCs and amphiphilic block copolymers as transport and barrier elements respectively, into scalable membranes are studied. A series of analyses on transport experiments and computer simulations indicated a strong coherence between nanoscale and membrane scale transport properties, demonstrating successful channel integration for molecular separations. Lastly, further insights on transforming the AWC structures to viable membranes for large-scale applications are presented, specifically targeting gas separations. Leveraging these studies, this dissertation intends to provide guidance to researchers on development of new bioinspired membranes.

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