Reprogrammable,
Reprocessible, and Self-Healable Liquid
Crystal Elastomer with Exchangeable Disulfide Bonds
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Abstract
A liquid
crystal elastomer (LCE) can be regarded as an integration
of mesogenic molecules into a polymer network. The LCE can generate
large mechanical actuation when subjected to various external stimuli.
Recently, it has been extensively explored to make artificial muscle
and multifunctional devices. However, in the commonly adopted two-step
crosslinking method for synthesizing monodomain LCEs, the LCE needs
to be well-cross-linked in the first step before stretching, which
increases the disorder of mesogenic molecules in the final state of
the LCE and makes it very challenging to fabricate the LCE of complex
shapes. In this article, we developed a new LCE with disulfide bonds,
which can be reprogrammed from the polydomain state to the monodomain
state either through heating or UV illumination, owing to the rearrangement
of the polymer network induced by the metathesis reaction of disulfide
bonds. In addition, the newly developed LCE can be easily reprocessed
and self-healed by heating. Because of the excellent reprogrammability
as well as reprocessability of the LCE, we further fabricated LCE-based
active micropillar arrays through robust imprint lithography, which
can be hardly achieved using the LCE prepared previously. Finally,
we showed an excellent long-term durability of the newly developed
LCE