This is a CAREER grant to fund research and educational activities aimed at examining the reaction-diffusion processes controlling the synthesis of mesoporous films through a vaporized precursor route. The PI plans to examine dominant synthetic reaction-diffusion processes to gain a fundamental understanding of the formation mechanisms and thus increase the potential for commercialization of the methodology.
Intellectual merit
Ordered mesoporous materials have been proposed for many applications including hybrid photovoltaic devices, sensors, low-k dielectric films, membrane separations, catalysts, optoelectronics, and environmental mitigation. The challenge for these materials is spatial control of the morphology and chemistry at the nanoscale across macroscopic dimensions in order to provide optimal performance for the desired application. Decoupling the self-assembly and reaction by utilizing preformed template films and introducing the reactive precursors through the vapor phase enables improved control of the formed nanostructures. However, the true potential of this technique has not been fully realized due to a lack of fundamental knowledge regarding the mechanism by which the reaction occurs. This work focuses on the in-situ characterization of the reaction within a thin film. A combination of tandem ellipsometry and quartz crystal microbalance measurements will be used to elucidate the synthetic mechanism and to develop a predictive model for the synthesis. These fundamental measurements and modeling will enable the rational synthesis of novel mesoporous materials for specific applications. Moreover, this fundamental knowledge will open up important commercialization prospects for the vapor based processing technique.
Broader Impact
The impact of this work will be demonstrated on three fronts. First, the understanding of the synthesis mechanism will enable the design of new mesoporous materials exhibiting desired properties for multiple applications, and thus will increase the commercial potential of mesoporous materials in new consumer products. Second, the research entails cross-disciplinary skill sets (materials synthesis, materials characterization and modeling), offering a highly interdisciplinary learning platform for graduate and undergraduate students involved in the research. Undergraduate juniors and seniors will be exposed to a nontraditional educational experience as they work independently on a small subset of the project. The third component of this work is outreach through assisting in the incorporation of nanotechnology concepts into the chemistry curriculum at Estrea Mountain Community College, which serves a significant fraction of first generation college students. Additional outreach to the K-12 level will include an educational tutorial on nanotechnology in consultation with a teacher at a central Phoenix elementary school. In this outreach effort, the students will be exposed to the interdisciplinary nature of modern research and use examples from research to highlight the relevance and interrelationship of science topics such as physics, chemistry and mathematics. Demonstrating connectivity and inter-dependency of these subject areas at an early age will help to promote long-term student engagement in science and math and the creation of a scientifically literate workforce. The materials developed with the teacher will be further disseminated through ASU?s Mathematics, Engineering, Science Achievement (MESA) program for K-12 students. MESA provides rigorous academic support to educationally disadvantaged students (in particular, underrepresented minorities) so they excel and graduate with baccalaureate degrees in math, science and engineering fields. The MESA program serves thirteen school districts in central Arizona including Ganado and San Carlos Reservations.
This project focused on understanding the chemical and physical aspects associated with the fabrication of porous carbons with very well defined structures on the nanoscale. These pores are templated by the assembly of large surfactants, similar soap, using the same polymer, phenolic resin, that is used to hold particle board together. This composite is then heated to high temperature to remove the surfactant and convert the polymer into carbon. The details of how these are assembled impact the final structure. If there is too little phenolic resin, the structure collapses, like a house of cards (see image of poorly ordered structure). With too much phenolic resin, the surfactant template does assemble into a periodic structure as there is too much material between them to sense each other. In the intermediate compositions, well defined structure emerge that provide a well defined pore size and geometry (see ordered structure). These well-defined structures provide potential advantages for a number of applications. Unlike the activated carbon used in typical water filters, these pores are much larger which allows for larger molecules such as dyes used in fabric or biological molecules to get inside of the porous structure. This enables improved sensitivity for the detection of glucose (for hypoglycemia) or products associated with performance enhancing drugs. How one assembles and processes these materials has a significant influence overall on the final structure and ultimately their properties. This work has demonstrated critical factors required to produce the desired structure as well as processing techniques that enable improvements on the perfection of the structure developed from the self assembly.
