<br/>Materials that reliably produce a mechanoresponse upon low-energy driven stimuli such as near infrared (NIR) (690 - 900 nm) or heating a few degrees above room temperature have significant technological implications. We are investigating two types of thermal mechanoresponsive systems that utilize conformational changes for power-efficient actuation. We have created a dynamic scaffold based on NIR stimuli-responsive polymer composites, i.e. a hydrogel made of poly(N-isopropylacrylamide) (PNIPAM) /graphene. A spatial light modulator coupled with an engineered porous structure to facilitate water diffusion enable spatially and temporally defined mechanical forces to be generated at a fast rate.  This new platform can potentially impose force induced by NIR actuation onto cells for influencing stem cell differentiation.<br/>We have revealed a new sub-molecular switch, a dibenzocyclooctadiene (DBCOD), a hinge that consists of a flexible eight-membered ring fused with two rigid phenyl rings. Like proteins, the conformational change can be triggered by a low energy stimulus such as NIR photon irradiation or heating a few degrees above room temperature. A polymer system that contains a small amount of DBCODs without any process optimization exhibits an anomalous giant thermal contraction. The thermal contraction value is about 10 times greater than that offered by the second best reported system. A new bilayer based on the DBCOD-containing polymer can offer high-efficient actuation. This opens a pathway for soft robotics applications.<br/>

Near infrared responsive polymeric actuator

255th National Meeting (2018)

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