Photoresponsive liquid crystalline elastomers (LCEs) have been widely studied. Numerous prior demonstrations document that light irradiation triggers deformation, often facilitated by isomerization of a photochromic moiety. Historically, azobenzene has been used as this photoisomerizable molecule, but this presents challenges due to the thermal instability of the <i>cis</i> isomer. Here, we seek to realize control and stability of photo-induced deformation in elastomeric materials through incorporation of diarylethene (DAE) in a liquid crystalline network.<br/><br/>Due to the thermal stability of both the open-ring and closed-ring isomers of DAE, we are able to generate photo-induced deformation via order disruption in liquid crystalline materials that is all-optically reversible and can be repeated over multiple cycles. Dynamic bonds are integrated in the polymer network to facilitate thiol-anhydride exchange, allowing for reprogramming of the nematic director between cycles as well as retention of deformed states. The coupling of the thermally stable photoresponse and rearrangeable network structure enables on-demand, controlled actuation of liquid crystalline elastomers capable of shape permanence.

Photoinduced deformation and shape memory in diarylethene-functionalized liquid crystal elastomers facilitated by thiol-anhydride dynamic chemistry

ACS Spring 2022

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