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Helen Yao

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Email: helenyao@princeton.edu

Status: Senior Thesis Student

Research Interests:

Block copolymers are known to self-assemble into a range of morphologies. We can tune this morphology by blending homopolymers into the block copolymers. Traditionally, blending studies have been done using discrete blend ratios; this can be cumbersome and time-consuming. Instead, I am studying the phase behavior of blended homopolymer-block copolymer systems using a higher throughput method which involves flowcoating a wedge (film with a thickness gradient) of the homopolymer and subsequently spin-coating a block copolymer layer of uniform thickness on top of the wedge. This technique allows for a gradient of blend ratios to be produced along a single film. The phase behavior can then be probed using an atomic force microscope by which morphological transitions can be easily detected. For this work I employ poly(sytrene-ethylene/butylene-styrene) (SEBS) triblock copolymers and poly(2,6-dimethyl 1,4-phenylene oxide), which exothermally mixes with poly(styrene), as the blending homopolymer.