Junior Roxy Kiessling wins ACS presentation Award!
Babak Sanii
Roxy Kiessling won the third place award for oral presentations in the Undergraduate Research in Polymer Science symposium, at the 2017 American Chemical Society Meeting in San Francisco. Her talk was on "Semi-flexible string conformational analysis towards an experimental hydrophobic-folding model system." Roxanna Kiessling2, Collin Barraugh2, Babak Sanii1 1. Chemistry, Claremont McKenna, Pitzer & Scripps Colleges, South Pasadena, CA, United States. 2. Claremont McKenna College, Claremont, CA, United States. Abstract: We study two-dimensional folding with elastomers extruded into strings, ~100μm wide and centimeters long. These strings are large enough for convenient experimental observation, and flexible enough to access a large number of folded conformations. We acoustically excite the strings at the air-water interface and optically image them to quantify conformational parameters. Semi-flexible or rigid strings produce histograms of end-to-end distances that are consistent with semi-flexible chain modelling, with well-defined persistence lengths. The choice of polymer (PDMS, polydimethylsiloxane) enables hydrophobicity patterning along the length of the string with ultraviolet-ozone radiation. We use water droplet-on-fiber contact angle measurements to assess the degree and longevity of string hydrophilicity introduced via this exposure. We have demonstrated that the UV-patterning of the string has a direct impact in its folding conformational statistics. We envision this system as a tunable experimental means of studying and designing complex folding pathways, with possible applications to molecular (bio)polymer folding problems.  


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