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Utilizing Solvatochromic Dyes to Probe Phase Changes in Stimuli Responsive Polymers – Elisa Castillo

REU student Elisa Castillo is conducting her summer research in the laboratory of Chemistry and Biochemistry Professor Lisa Kelly on stimuli responsive polymers.




REU Student Elisa Castilloa (right) with Graduate student mentor Stacey Tova (middle) and Faculty mentor Prof. Lisa Kelly (left) in Prof. Kelly’s laboratory.




Solvatochromic dyes change color (absorption and fluorescence) in an array of variant environments and report real-time changes in their surroundings. Solvatochromic dyes are able to accomplish this by responding to differences in solvent polarities. Therefore, by utilizing these dyes one is able to more accurately analyze interactions between solvents and solutes on a molecular level. Significantly, these dyes can analyze the effects environmental conditions have on biological molecules and other materials such as stimuli responsive polymers. Stimuli responsive polymers are polymers that adapt to the environment in which they are located. In addition, these “smart polymers” are capable of regulating the transportation of molecules, may alter certain properties (such as adhesion), and can transform chemical signals into electrical, thermal, mechanical, and visual information. These polymers are of particular interest because they are able to adapt to changing conditions. They respond to these alterations by undergoing phase changes. These polymers exist in a variety of forms. In this research they are present as sub-micron sized hydrogels (cross-linked polymers) that we call nanogels.

The aims of this project are to (i) synthesize novel solvatochromic dyes and (ii) covalently incorporate them into nanogels to track phase changes in the stimuli responsive materials. The synthesis of the dyes is shown below:


Figure 1. Synthesis of dye

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Figure 2. Compound (I) and nanogel

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                                                                   110°C, 1.5 h


The absorption and fluorescence properties of compound (I) will be studied in solvents of varying polarities. In addition, fluorescence from the dye-labeled nanogels will be characterized above and below the lower critical solution temperature (LCST) to demonstrate that they can be used to probe real-time changed in the phase of a polymer.