Wui Siew Tan

Research Summary

My research focuses on combining the solution self assembly of block copolymers with electrostatic Layer-by-Layer assembly (LbL) to create nano-structured, stimuli responsive thin film coatings.

Thermo-mechanically responsive surfaces in aqueous environments are interesting for various biological applications. Our paper "Temperature-Induced, Reversible Swelling Transitions in Multilayers of a Cationic Triblock Copolymer and a Polyacid" describes how (1) different solution aggregation states of the cationic triblock copolymer and (2) the polyacid selection has a determinative effect on the temperature response of thin films assembled. Specific assembly conditions used to obtain a loose ionic network surrounding micelles enabled > 400% fully reversible swelling to be achieved.

Fundamental studies seeking to understanding the molecular level molecular weight and connectivity effects on the temperature response of these films are ongoing with our collaborators at Steven's Institute of Technology.

Temperature controllable wetting, modulus and physical dimensions make these coatings attractive active surfaces. They can be used to gate of membranes for size / charge selective separations. In addition, these coatings offer heterogeneous surfaces with nano-scaled hydrophilic and hydrophobic switchable patches, making them interesting subjects for studying attachment, migration or diffusion, and release of cells or proteins.