Liquid
crystalline elastomers (LCEs) have emerged as an important
class of functional materials that are suitable for a wide range of
applications, such as sensors, actuators, and soft robotics. The unique
properties of LCEs originate from the combination between liquid crystal
and elastomeric network. The control of macroscopic liquid crystalline
orientation and network structure is crucial to realizing the useful
functionalities of LCEs. A variety of chemistries have been developed
to fabricate LCEs, including hydrosilylation, free radical polymerization
of acrylate, and polyaddition of epoxy and carboxylic acid. Over the
past few years, the use of click chemistry has become a more robust
and energy-efficient way to construct LCEs with desired structures.
This article provides an overview of emerging LCEs based on click
chemistries, including aza–Michael addition between amine and
acrylate, radical-mediated thiol–ene and thiol–yne reactions,
base-catalyzed thiol–acrylate and thiol–epoxy reactions,
copper-catalyzed azide–alkyne cycloaddition, and Diels–Alder
cycloaddition. The similarities and differences of these reactions
are discussed, with particular attention focused on the strengths
and limitations of each reaction for the preparation of LCEs with
controlled structures and orientations. The compatibility of these
reactions with the traditional and emerging processing techniques,
such as surface alignment and additive manufacturing, are surveyed.
Finally, the challenges and opportunities of using click chemistry
for the design of LCEs with advanced functionalities and applications
are discussed.