Design and Construction of Responsive Surfaces by Means of Tethered Chain Nanolayers

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Lynn S. Penn, Et al, University of Kentucky"Design and Construction of Responsive Surfaces by Means of Tethered Chain Nanolayers"This project explores use of a tethered chain strategy to create surfaces that respond dynamically to their environments or other external stimuli. (A tethered chain is defined as a polymer molecule that is attached by a single point along its length to the surface of a solid.) Tethered chains are uniquely suited for creating responsive surfaces because, except for chain segments adjacent to the point of attachment, their segmental mobility is not impaired. Thus, even though they are attached permanently to the substrate, tethered chains can change conformation-- and thereby change the nature of the surface-- in response to an applied field or alteration in the local environment.Tethered chains of the appropriate chemical structure and molecular architecture, and with specific chemical functionalities attached, can be used to construct surfaces that exhibit a wide variety of responses. Surfaces can be constructed to have dynamic capabilities such as reversible appearance of nanoscale patterns, trapping of hazardous biological or chemical agents, and mimicry of surface energy of contacting phases. Surfaces with these capabilities have applications in electronics manufacture, clean-up of environmental pollution, biomedical devices, adhesive bonding, sensors in scientific instrumentation, adhesion and wetting, and biological and chemical warfare defense.In this project the investigators will gather the remaining experimental data needed to broaden their current mathematical model of the tethering process and make it versatile enough for practical use and will use controlled tethering to construct three demonstration surfaces that exhibit diverse response capabilities. The three demonstration surfaces will be able to 1) exhibit reversible, in-plane phase separation in response to temperature changes, 2) trap large anionic species from a passing stream, and 3) change surface energy to match that of a contacting phase, respectively. Project activities include synthesis of large organic molecules and polymers, execution of tethering procedures under controlled conditions (with real time monitoring), and characterization of structure and function of the surfaces by means of a variety of techniques.Impact: The modification of surfaces with polymers to manipulate nano-surface structure and properties is technologically important on many fronts. This work addresses a critical need. The training provided in these sophisticated techniques will enable research in this important nano-technology to expand. The networking between departments and universities proposed in this proposal is considered to fully utilize the advantages of multidisciplary approaches and inculcates this approach in the formation of the many students involved. If the research is successful, new responsive surfaces will be available for a wide variety of important nano-technological applications which will provide great benefit to society.