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Figure 1. A 20 wt % aqueous solution of a thermo- and pH

Active Control of Sol-Gel-Sol Transitions of Aqueous Solutions of Doubly Responsive Hydrophilic Block Copolymers Bin Zhao, University of Tennessee Knoxville, DMR 0906913.

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Figure 1. A 20 wt % aqueous solution of a thermo- and pH

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  1. Active Control of Sol-Gel-Sol Transitions of Aqueous Solutions of Doubly Responsive Hydrophilic Block CopolymersBin Zhao, University of Tennessee Knoxville, DMR 0906913 Aqueous micellar gels of stimuli-responsive block copolymers are being used in drug delivery, tissue engineering, etc. With the demand of new materials increasing, there is a need for multi-responsive block copolymer gels. We have developed a unique strategy for the design and synthesis of doubly responsive hydrophilic block copolymer gels. The unique feature of these block copolymers is that the lower critical solution temperatures (LCSTs) of thermosensitive blocks can be modified by external stimuli, enabling active control of sol-gel/gel-sol transitions. Figure 1 shows a 20 wt % aqueous solution of a doubly thermosensitive diblock copolymer with the higher LCST block incorporated with a small amount of weak acid groups under different conditions. Evidently, the gel-to-sol and clear-to-cloudy transitions can be tuned. Figure 1. A 20 wt % aqueous solution of athermo- and pH -sensitive diblock copolymer (see Scheme 1 for structure) Macromolecules2011, 44, 3556; 2011, 44, 5764; 2009, 42, 8468. J. Phys. Chem. B.2011, 115, 2870. Langmuir2011, 27, 2019; 2010, 26, 8787. Soft Matter 2010, 6, 3325. Scheme 1. Synthesis ofmultiresponsive diblock copolymer

  2. Active Control of Sol-Gel-Sol Transitions of Aqueous Solutions of Doubly Responsive Hydrophilic Block Copolymers Bin Zhao, University of Tennessee Knoxville, DMR 0906913 Education Under current & previous grants, four students have graduated with Ph.D. degrees (Thomas O’Lenick, 2011; Xueguang Jiang, 2010; Xiaoming Jiang, 2010; Dejin Li, 2008). Three students are pursuing their Ph.D. degrees: Jeremiah Woodcock (5th year), Jonathan Horton (4th year), and Naixiong Jin (3rd year). Four undergraduates participate in this project (R. Wright, M. Gindt, S. Goddard, and M. Bowman). • Outreach • Organized a tour to our lab and department for 7 students from two local high schools in June, 2011, and presented a lecture on Introduction to Polymers and five polymer lab demos. • Hosted two high school teachers, Debbie Fraser and Debbie Sayers, in the lab for two weeks in the summer of 2011. • Hosted one high school student, Amie Guo, in the lab in the summer and fall semesters of 2009 and guided her to complete a project on thermosensitive hydrogels. High school students are making superball and slime in our research laboratory.

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