Fabrication of Gold-Loaded Nanoreactors By Polymer Directed Self Assembly

Tien Vuong

Andrew Harrison, Dr. Christina Tang

School of Engineering, Department: Chemical and Life Science Engineering

Introduction: Liquid phase chemical processing is commonly used for production of fine chemicals and pharmaceuticals. Large amounts of organic solvents are required, which generates a large amounts of hazardous waste. Multifunctional polymer nanoreactors that contain gold nanoparticle catalysts that combine reaction and separation could improve efficiency and minimize hazardous waste for liquid-phase reactions. Confining gold nanoparticles to the nanoreactor core can accelerate reaction rates due to enhanced local concentrations of the reactants and product isolation occurs by spontaneous phase separation.

Methods: Polymer nanoreactors that contain gold nanoparticle catalysts were achieved by encapsulating pre-synthesized gold nanoparticles with various hydrophobic co-precipitants using Flash NanoPrecipitation, a polymer-directed self-assembly method. Co-precipitants investigated were: polystyrene, Vitamin E, trioctylamine, dodecanethiol, and dodecane. The structure of the nanoreactors has been analyzed by with dynamic light scattering (DLS), transmission electron microscopy (TEM) imaging, and UV-Vis spectroscopy.

Results: Gold-loaded, polystyrene-based nanoreactors between 50 nm and 300nm were achieved by varying the formulation. Specifically, the nanoreactor size and the catalyst loading was tuned by changing the concentration of the core materials (gold nanoparticles and polystyrene), the concentration of the copolymer stabilizer (polystyrene-b-PEG), or the total material concentration. The nanoreactor size can be tuned independent of gold loading by changing the total material concentration. Gold loading (nominal) can be tuned independent of nanoreactor size by changing the ratio of gold nanoparticles to co-precipitant. The size of the polystyrene-based nanoreactors was stable in water and the presence of base.

Conclusions: Polystyrene nanoreactors loaded with gold nanoreactors have been prepared by encapsulating pre-made gold nanoparticles with various hydrophobic co-precipitants. Gold-loaded nanoreactors between 50 nm and 300 nm were achieved by varying the formulation parameters. The nanoreactor size and gold nanoparticle loading were varied independently. Currently, we are investigating the effect of the co-precipitant on nanoreactor stability and quantifying gold loading.