Tuning Aqueous Micellar Gels and Nanoparticle-Containing Hybrid Micellar Gels of Thermosensitive Hydrophilic Block Copolymers

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TECHNICAL SUMMARY:Aqueous micellar gels of stimuli-responsive hydrophilic block copolymers have attracted growing interest in recent years due to the intriguing in situ sol-gel transitions induced by environmental triggers. These physical gels have great potential in many technological applications. This project is aimed at developing strategies to tune structures and properties of aqueous micellar gels of doubly thermosensitive block copolymers and of aqueous hybrid micellar gels of thermosensitive block copolymers and nanoparticles. A series of well-defined multi-responsive hydrophilic block copolymers and polymer brush-grafted nanoparticles ("hairy nanoparticles") will be synthesized by using "living"/controlled radical polymerization techniques. The responsive properties of these block copolymers and hairy nanoparticles in aqueous solutions will be examined. The sol-gel phase diagrams of thermosensitive block copolymers in low/moderate concentration ranges in the absence and presence of hairy nanoparticles will be determined, and the gel structures will be elucidated. A wide range of characterization techniques will be employed in this research, including light scattering, rheometry, fluorescence spectroscopy, small angle X-ray scattering, differential scanning calorimetry, and electron microscopy. The knowledge gained from this research will provide a basis for the design of a new class of multi-responsive block copolymer micellar gels and hybrid micellar gels with tunable structures and properties for technological applications. NON-TECHNICAL SUMMARY:This project involves creating special categories of water-soluble gels that form micelles and nanoparticles. These new materials will be designed to respond to a variety of external stimuli and could have potential applications for sustained and triggered release of substances. Moreover, this research project provides a solid platform for training graduate and undergraduate students to synthesize and characterize a variety of new molecules and nanostructures by a broad range of techniques and to design stimuli-responsive soft and hybrid materials. Students will have an opportunity to gain a deep understanding of relationships among synthesis, structures, and properties. The PI will continue his effort to develop and enrich a laboratory component for the introductory polymer chemistry course in the Department of Chemistry at the University of Tennessee, Knoxville. The PI will also be active in helping science teaching in K-12 education. He and his graduate students will work with local high school teachers and students in his laboratory through summer programs to develop laboratory experiments for their chemistry classes.