CAREER: Amphiphilicity-Driven Organization of Nanoparticles into Discrete Assemblies

William Marsh Rice University, Houston TX

Investigators

Abstract

TECHNICAL EXPLANATION This CAREER project will use the hydrophobic effect as a means to assemble condensed matter into discrete functional objects. Specifically, covalent attachment of Y-shaped amphiphiles to metallic clusters of platinum (Pt), palladium (Pd), and gold (Au) will impart the amphiphilicity to the resulting hybrid structure. Because every particle will be the junction point of all hydrophobic and hydrophilic arms, the micellization will lead to a dense packing of particles exactly at the boundary between the core and corona of the micelle. Thus, the individual particles will organize spontaneously into finite and well-defined nanoarrays. Importantly, each micelle will be a carrier of densely packed catalytic sites (Pt, Pd, or Au nanoparticles) and will combine the best features of homogeneous and heterogeneous catalysts. We hypothesize that the catalytic activity may not only be a function of size and the nature of particles, but will also depend on the curvature of nanoarrays and the degree of order in them. The curvature can be dramatically changed as cylinders transform into vesicles, and vice versa. Thus, the catalytic activity and/or selectivity may be manipulated by changing the morphology of the proposed assemblies. The expected outcomes are strongly supported by the feasibility studies on gold nanoparticles, but the approach can be applied to any spherical or rodlike carrier of functionality. NON-TECHNICAL EXPLANATION The broader impacts of the project are in developing new methods to bridge the gap between the nano- and mesoscale, and to strengthen the nanoscience education of the general public in Texas and nationwide. Of particular importance will be the collaboration with the NSF-funded educational outreach program NanoKids. The PI will introduce a Materials Studio Visualizer Program in the middle schools that are already using NanoKids educational materials. This 3D Molecular Graphics Program will allow children to learn and better understand the structure of various molecules, crystals, and DNA. In a parallel effort, three on-line mini-courses in nanotechnology, which will be used by 58 science teachers from the greater Houston area, will be developed. Unique hybrid structures and advanced catalysts proposed in this project will be excellent examples to help K-12 teachers understand the origin of unusual properties of matter at the nanoscale, and to learn about the industrial and societal implications of nanotechnology. This project will open up a new avenue for organizing functional matter and creating better catalysts, which will directly benefit society.