The Division of Chemistry supports Scott Shaw of the University of Arizona as an American Competitiveness in Chemistry Fellow. Dr. Shaw will work with Prof. Jeanne Pemberton to investigate the liquid-solid interface between a broad range of solvents and polymer materials. The research will use a variety of optical methods to probe very thin films of the solvents deposited on polymer surfaces. Additional work will be carried out in collaboration with Dr. Lime Dang, a theorist at Pacific Northwest National Laboratory. For his plan for broadening participation, the PI will work with a number of student social groups on the University of Arizona campus, as well as other community groups off-campus. The bi-monthly activities will engage a broad community (age, economic, etc.) in discussions of the results of current scientific discoveries and their relevance to problems in society.
Research like that of Dr. Shaw is aimed at developing a better understanding of how solids and liquids interact at the solid-liquid boundary. Results from research like that supported here will lead to better devices (e.g. medical diagnostics), better industrial processes (e.g. chemical processing), better strategies to prevent ship fouling, as well as other important applications. The efforts at broadening participation being pursued by Dr. Shaw are aimed at engaging a broad cross-section of American society in discussions of science and its impact on society. The hope of activities like these is to develop an engaged, scientifically-literate citizenry.
A comprehensive list of defining characteristics to describe polymer behavior at surfaces is lacking which impedes the development of new devices and materials. To overcome this hurdle in materials development, this project examined surfaces modified with thin films of polymers and studied them in contact with various fluids to accurately describe the interfacial characteristics at a molecular level. The primary objective of this proposal has been to create a detailed understanding of inter-molecular interactions of fluids at polymeric surfaces through combined efforts of experimental and computational methods. Results have been particularly informative to nascent fields such as micro and nano-fluidics and conductive-organic devices. In particular, a series of measurements on aqueous thin films has been determined to show a distinct trend in the degree of a specific intermolecular force, known as hydrogen bonding, that varies directly with the film’s thickness (between 0.5 nm and 2.5 nm thick). This thickness corresponds to a range of approximately 5 to 15 molecular layers of water. Also, a platform for measurements and simulations of incrementally perturbed interfacial fluid structures created by the adsorption of small charged molecules and surfactants has been developed, which will be examined in future studies. These will be created by very common, but poorly understood, polymer surface modification techniques. Combining these perturbations will afford a wide continuum of surface chemistries available for study, ultimately allowing surfaces and fluids to be paired together to create a tunable range of interactions and producing a model to better guide future device design. In parallel with the experimental work described above, the investigator became an expert in several specialized analytical techniques. This expertise will be used to carry out future studies and will be taught to other students in the field. The investigator also had the opportunity to travel to several national laboratories and formed collaborations with staff scientist at the Oak Ridge National Laboratory and the Pacific Northwest National Laboratory. Both of these collaborations added significantly to the research being carried out by providing access to detailed calculations of the intermolecular forces (Oak Ridge) and performing additional analysis of the system (Pacific Northwest) using techniques that would have otherwise been unavailable. Durin the period of this award, the investigator also initiated a public outreach program called 'Science for Seniors'. This program provided the recently retired population (prevalent in the local community) with a variety of 30 minute presentations of topics relevant to the physical sciences that appeared in the popular media at the time. Specific topics of presentations included solar energy, copper mining practices, and monitoring carbon dioxide levels.
