Nanoscience and Materials Chemistry
The manipulation of matter on the nanometer scale has become a central focus from both fundamental and technological perspectives. Unique, unpredictable and highly intriguing physical, optical and electrical phenomena can result from the confinement of matter into nanoscale features. In our laboratory, we are working on synthesizing, characterizing and applying a range of different nanoscale structures, some of which are outlined here.
Nanoscale structures for solar energy
One of humanity’s foremost challenges is satisfying our ever-growing demand for secure, clean energy. As the earth’s population is projected to reach nearly 10 billion by 2050, global energy consumption is expected to increase commensurately, with at minimum a two-fold increase by 2050. In raw demand, this is an increase from the present consumption of 13.5 terawatts (TW) to at least 27 TW. In this research program, we direct our efforts towards a multidisciplinary approach, with the goal of utilizing inexpensive conducting polymers (some of which we design and make in-house), and highly abundant, inexpensive "rock-like" materials. These materials are combined into a manufacturable third generation photovoltaic technology. By building multilayer films of inorganic nanoparticles in a highly controllable fashion, we focus upon the production of both excitonic and dye-sensitized cells. The program builds upon a highly interdisciplinary team consisting of an industrial partner, industry and government laboratory supporters, and university and government collaborators.
Using self-assembly to build sub-50 nm features on silicon
Fabrication of nanoscale features integrated with a range of technologically important semiconductor surfaces, on a sub-100 nm length scale, is a rapidly growing area of research with respect to future semiconductor applications, including hybrid semiconductor-organic and nanoparticle devices, tissue integration, molecular electronics, micro- and nanofluidics, sensing, photovoltaics, and others. Lithography is the single most expensive cost factor in chip manufacturing. To be considered viable from a commercial perspective in the near to mid-term, and beyond, new lithographic approaches should ideally be compatible with existing silicon-based micro- and nanofabrication techniques, presently in operation. Because of the ubiquity of polymers in silicon fabrication (as photoresists, for example), polymer self-assembly to produce nanoscale structures has recently emerged as a possible approach to the production of uniformly patterning broad areas of surfaces. Block copolymer self-assembly is explicitly mentioned in the Semiconductor Industry Association Roadmap as a potential "innovative technology" may be utilized to produce sub-45 nm features on integrated circuits (ICs). In this project, we are developing a number of ways to “convince” block copolymers to form beautiful, complex and useful patterns, with the goal of integrating these processes into chip manufacturing lines on silicon.
Recently, nanoparticles (NPs) have come to the forefront as potential catalysts for a wide variety of reactions including olefin and arene hydrogenations. NP catalysts are advantageous for many reasons including high surface areas and energies, unique electronic effects and potentially lower cost: high surface to volume ratios mean less metal is ‘wasted’ in the particle interior, and higher selectivity produces fewer undesirable side products. In this project, we build combinatorial libraries of heterogeneous catalysts for a number of hydrogenation reactions to discover leads to highly active and previously undiscovered catalysts.
Nanoscale patterning via stamp lithography
Considerable effort has been ongoing in recent years to improve and build upon the ability of various patterning techniques. Our approach towards this challenge has been the introduction of catalytic stamps, poly(dimethylsiloxane) (PDMS)-based stamps integrated with nanopatterned transition metal catalysts. Using these functional stamps, a variety of catalytic reactions have been carried out on Si surfaces, and molecular patterns with down to 15 nm resolution have been produced. Reactions include hydrogenation, hydrosilylation, Click chemistry, and Heck reactions.
Nanomedicine and Transplantation
Through a collaboration with a highly multidisciplinary team, we are producing the vehicles that could help prevent organ rejection in humans through a immunogenic process called “tolerance”. We hope to solve the problem of blood group incompatibility via the development of nanoparticles and stents that are functionalized with the very blood group antigens that induce organ rejection. Through application of these materials at the precise time in an infant’s life when the immune system is still learning (up to about 24 months of age), we hope to promote tolerance in the individual, thus lessening the chances of organ rejection later in life, should the need arise.