Title: Photothermal Heating with Nanoparticles: Enhancing Electrical Conductivity in Composites and Water Vapor Formation in Hydrogels

Abstract: Photothermal heating is the conversion of light into heat. When nanoparticles are embedded in materials, we are able to precisely control localized heating in a sample using photothermal heating of the nanoparticles. We use this heating in two areas to enhance material properties and processes. We will first discuss carbon nanotube polymer composites, which are desirable for their high electrical and thermal conductivity. However, in order to form a percolated network, nanotubes are coated with a surfactant to improve dispersion, thus diminishing the ideal conductivity of the composite. Our work uses surfactant to disperse multi-walled carbon nanotubes (MWCNTs), then utilizes photothermal heating of the MWCNTs to remove inter-particle material to enhance the conductivity. We will also present work on water vapor formation in hydrogels. Hydrogels have been studied as a driver in water purification processes and we propose using photothermal heating of nanoparticles to aid in water recovery step of these processes. We photothermally heat a sodium acrylate and N-isopropylamide hybrid embedded with gold and melanin nanoparticles and show changes in water vapor output efficiency when compared to traditional oven heating. We further investigate the photothermal capabilities of melanin nanoparticles as a biologically compatible photothermal heater. These findings utilize the same fundamental mechanism- photothermal heating- to offer potential improvements for industrial and humanitarian efforts alike.