Walter F. Paxton
Soft Nanotechnology. Research in the Paxton Lab is all about understanding the self-assembly of polymers into dynamic nanostructures. Materials like this can form assemblies that respond to environmental stimuli – like changes in temperature, pH, or chemical potential. In our group we are using these materials to control the chemical and electronic properties at liquid-solid interfaces.1 We also use catalysis – including enzymes – to change the properties and morphologies of these self-assembly nanomaterials.
Tuning the Chemical and Electronic Properties of Interfaces. Some polymer amphiphiles readily adsorb and fuse to hydrophilic surfaces to form layered structures with tunable thicknesses on the nanometer scale.2 These adsorbed layers may be used as models of cell surfaces and also allow tuning the chemical properties of interfaces. Understanding how these adsorbed layers change the electronic properties of interfaces can be especially important for developing new kinds of sensors. Paxton students interested in this area will develop expertise in forming supported polymeric and hybrid (lipid/polymer) bilayers and measuring their electronic properties using electrochemical methods, like cyclic voltammetry.
Integrating Biological Function in Stimuli-Responsive Vesicles and Bilayers. We are also interested in creating materials that change their shape to favor the dynamic transformation between micelles, bilayers, and other structures depending on their local environment. Stimuli-responsive polymers coupled to heterogeneous catalysts, including enzymes, make it possible to translate chemical signals into physical changes to self-assembled nano-structures. Clever designs of such systems would enable the development of bio-hybrid “cyborg materials” that respond via catalysis to stimuli that are (otherwise) unrelated to the normal stimuli these materials are sensitive to. Such materials would find tremendous value as self-actuating nanomaterials.
Electricity from Sugar. We are also developing a new kinds of reusable electrode that can turn carbohydrates into electricity.3 Early results are promising for developing a new kind of reusable fuel cell that can turn wasted carbohydrates from food production (like the 2 million metric tons of whey permeate produced in the US each year from the Greek yogurt industry) into energy, turning food WASTE into electrical WATTS.
- Paxton et al. “Self-Assembly/Disassembly of Giant Double-Hydrophilic Polymersomes at Biologically-Relevant pHs,” Commun. 2018, 54, 9043-9046.
- Willes, K. L.; Genchev, J. R.; Paxton, W. F. “Hybrid Lipid-Polymer Bilayers: pH-Mediated Interactions between Hybrid Vesicles and Glass,” Polymers, 2020, 12, b) Paxton et al. “Adsorption and Fusion of Hybrid Lipid/Polymer Vesicles onto 2D and 3D Surfaces,” Soft Matter, 2018, 14, 8112-8118.
- Paxton, W. F.; Humphries, P. A.; Scott, D. D. V.; Han, H.; Bhowmik, P. K. “Electrocatalytic Oxidation of Carbohydrates via Surface-Immobilized Viologen,” Electrochem. Soc. 2021 (accepted).