Porous Polymer Membranes

Polymer membranes are used in many fields, from water filtration to energy materials. They represent a low-cost, easily manufactured material with highly tuneable properties which can be targeted at the chosen application. 

We use different additives as part of a non-solvent induced phase separation method to produce polyethersulfone ultrafiltration membranes. Our focus is on changing the microstructure of these membranes to create multiple levels of structural hierarchy through use of template molecules. 

Our recent work uses a functionalised azobenzene additive to produce a fibrous structure at the micron scale, with the aim of increasing membrane surface area and permeability without compromising pore size.  We are investigating other templating molecules, including solar absorbing molecules to allow use of the membrane geometry in a solar steam generator.

3D reconstruction of polyethersulfone membrane using computer tomography (left) and cross-sectional electron microscopy image (right). Figure courtesy of Tom Southern.

To characterise these membranes, we use a variety of imaging techniques to study the samples at different length scales. These include X-ray computer tomography and scanning electron microscopy. Using tomography allows the analysis of samples in 3D. This is very important for the characterisation of membrane pore structure and allows a depth of analysis that more conventional cross-sectional imaging does not allow.