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Page 8 of 26 Xiao et al. Soft Sci 2023;3:11 https://dx.doi.org/10.20517/ss.2023.03

Figure 4. Thermal actuation of LCEs. (A) Versatile shape morphing capabilities of LCEs by designing the local LC alignment and
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incorporating the non-actuation domain. Scale bars, 2 mm. Reproduced with permission . Copyright 2018, WILEY-VCH; (B)
illustration of the room-temperature embossing of LCE films, and the reversible actuation of the processed LCE film. Scale bars, 5 mm.
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Reproduced with permission . Copyright 2005, The Royal Society of Chemistry; (C) FEA simulations and optical images of the LCE
actuator composed of two different LCE layers through the 4D-printing method. The light and dark blue regions denote two phases with
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different light exposure times (9 and 16 s) during the crosslinking process. Scale bars, 5 mm. Reproduced with permission . Copyright
2021 Wiley-VCH GmbH; (D) LCEs with embedded channels, which can be actuated through water heating/cooling. Reproduced with
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permission . Copyright 2020, American Chemical Society.
modes [95-98] . Figure 5B shows that the LCE incorporating Au nanoparticles (AuNPs) can realize a
photo-induced bending . The patterned regions are doped with AuNPs to act as “hinges” in response to
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waveguided visible light. The bending angles of > 14° can be achieved on the timescale of seconds. Complex
bending deformations can be activated through a judicious choice of active placements. Moreover, organic
dyes can also serve as photothermal agents [13,99-102] . The organic dyes can absorb quasi-daylight source while
maintaining good actuation performances. Furthermore, LCEs show compatibility with CPs responsive to
near-infrared light, and therefore, the LCE/CP composites can convert near-infrared light to heat
efficiently [103,104] . The CPs are hard to aggregate in the LCE, which thus enables an easy synthesis and
processing of LCE/CP composites.

The LCE-based composites capable of absorbing near-infrared light can be used in biomedical
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applications . Besides, the photothermally responsive LCEs can achieve high-precision spatial control by
moderating the light intensity [106,107] . However, the nanoparticles tend to concentrate in LCEs, and such a
concentration could evidently stiffen the LCEs, thereby limiting their deformability. For a thick LCE film
exposed in the irradiation, a nonuniform temperature rise along the thickness direction could occur, which
may induce an undesired bending deformation.