Photo-responsive soft materials that retain the responsive optical anisotropy of liquid crystals can serve as mechano-optic actuators for applications that include non-invasively steering fiber optics for biomedical applications. Here we report that reproducible thermoreversible networks are formed by self-assembly of coil-liquid crystal-coil triblock copolymers: the coil (polystyrene) end-blocks phase segregate from the liquid crystal midblock, forming of uniform and uniformly-spaced physical crosslinks, These polymers are elastic in the melt (at room temperature) and can be easily molded into desired shapes. Starting from identical triblock prepolymers (with polystyerene end blocks and 1,2-polybutadiene midblocks), a matched pair (3% azobenzene, and no azobenzene) of liquid crystal triblock copolymers was synthesized. These triblocks were then blended to prepare a series of elastomers with 0 to 3% azobenzene groups, while matching in nearly all other physical properties (cross-link density, modulus, birefringence, etc.), and photo-response was quantitatively measured, allowing us to isolate the effect of concentration of photo-responsive azobenzene groups on photo-response.

Moldable photo-responsive elastomers from thermoreversible networks formed by triblock copolymer self-assembly

253rd National Meeting (2017)

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