The Analytical and Surface Chemistry (ASC) program of the Division of Chemistry will support the research program of Prof. Gang Yu Liu of the University of California Davis. Prof. Liu and her students will study the mechanism and kinetic properties of nanografting and use these finding to regulate the outcome of surface reactions and self assembled monolayers (SAMs) formation on surfaces. The experimental approaches developed during the course of this study such as advanced nanofabrication methodology, molecular resolution imaging and structural characterization and qualifications of mixed self assembled monolayers will benefit the fields of nanotechnology and SAMs-based chemistry and biochemistry. The study will provide excellent educational training opportunities for graduate students and postdoctoral trainees in the cutting edge area of nano-scale resolution chemical imaging.
Report to public NSF CHE-0809977 PI: Gang-yu Liu Department of Chemistry, University of California, Davis, CA 95616 The goal of this research is to construct model systems to better mimic biological membranes. Using self-assembled chemistry, atomic force microscopy based imaging and nanofabrication capabilities, the team has developed advanced research methodologies to regulate surface reactions at the molecular level, and as such to produce model monolayer systems with the designated structure complexity to mimic and in some cases better the performance of model membrane systems. Specifics follow: Technical Merit Conventional methods of making thin film materials use "mix-and-grow", in which the products are the result (interplay) between the reaction kinetics and thermodynamics. This research developed a method known as nanografting, in which a sharp tip (nanometer) removes molecules from surfaces to exposure new surface region, above which reactants of designed component and concentration would come and fill the void space, as guided by the shaving trajectory. Advantages of this method include (a) reactions much faster than by conventional counterparts; and (b) the surface reaction products (e.g., thin film materials) exhibit different structures, whose local heterogeneity can be controlled by our conditions, that is, area of exposure. This size-dependent behavior manifests into different reaction pathways and an enhancement of reaction kinetics in nanografting, and can be utilized to regulate surface reactions to our designated outcomes. Broader Impact While the public is relatively well aware of nanoscience and nanotechnology in the context of size-dependent electronic and optical properties of quantum dots, analogous behavior in surface chemistry is under-emphasized. Three graduate students, three undergraduate students, and two postdoctoral researchers have worked directly on this project. All team members have mastered skills and acquired knowledge in (a) high-resolution imaging using state-of-the-art AFM and scanning tunneling microscopy (STM); (b) advanced skills in AFM-based nanolithography; (c) in-depth views of the self-assembly reaction mechanism, kinetics, and thermodynamics; and (d) applications of SAMs in nanotechnology. Twelve peer-reviewed publications have been generated, with more to come in the near future. Three Ph.D. thesis and two B.S. senior research works were enabled by this NSF support. Example nanostructures are shown in the images attached. The grant also enabled the team to establish international collaborations in conjunction with University of California’s 10+10 Alliance Program with China, and continue our collaborations with local community colleges. Students from Sacramento City College worked in the research laboratories during summer months. The results were reported to high school students during summer workshops such as COSMO and the ACS SEED project at UC Davis.
