Recently, The Ji Yan's team from the The Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology (Ministry of Education), Department of Chemistry Tsinghua University achieves significant progress in the field of soft actuators for liquid crystal elastomers.

https://doi.org/10.1002/adma.202400286

The team published a paper entitled "Cloth-to-Clothes-Like" Fabrication of Soft Actuators in the journal Advanced Materials after obtaining relevant data from the experiments using the RM257 material provided by our company (Hunan Chemfish Pharmaceutical Co., Ltd). Here a straightforward “cloth-to-clothes-like” method to prepare soft actuators with a low threshold by combining the hysteretic behavior of liquid crystal elastomers (LCEs) with the exchange reaction of dynamic covalent bonds, is proposed.

https://onlinelibrary.wiley.com/doi/10.1002/adma.202400286

Inspired by adaptive natural organisms and living matter, soft actuators appeal to a variety of innovative applications such as soft grippers, artificial muscles, wearable electronics, and biomedical devices. However, their fabrication is typically limited in laboratories or a few enterprises since specific instruments, strong stimuli, or specialized operation skills are inevitably involved, it is difficult to mass produce and generalize applications. A free-forming preparation method for soft actuators is lacking.

As a post-synthesis method, this strategy effectively separates the production of  LCEs and soft actuators. LCEs can be mass-produced in bulk by factories or producers and stored as prepared, much like rolls of cloth. When required, these LCEs can be customized into soft actuators as needed. This strategy provides a robust, flexible, and scalable solution to engineer soft actuators, holding great promise for mass production and universal applications.

Liquid crystal elastomers (LCEs) are chosen for “cloth” due to their exceptional hysteretic behavior. The π-π stacking of mesogens induces additional nematic interactions between polymer chains, resulting in internal network constraints and causing the hysteresis behavior. The exceptional hysteretic behavior of the LCEs is responsible for the residual stretch observed upon unloading. It is proposed that the rotation of the local liquid crystal director along the loading axis allows for the absorption of significant amounts of mechanical energy, thereby ensuring the strain history (after undergoing deformation) of LCEs well preserved even after being released from external stress. Past approaches using only dynamic covalent bonds do not allow for this strategy. The obtained LCEs material deformed to the target shape and the shape was able to be maintained by withdrawing the external force immediately after deformation. The retained shape can be permanently memorized at ambient temperatures if left undisturbed for an extended period.

The research hold promise for promoting soft actuators from laboratory to versatile usage and mass production in the future. After purchasing "cloth",  individuals can freely tailor soft actuators for a wide range of scenarios, akin to the way cloth is made into various household fabrics and everyday items. For industrial manufacturing, this production process can be further streamlined, resulting in a simplified and well-established production system that facilitates control and coordination to achieve consistent and continuous manufacturing. This fabrication strategy anticipate to open up considerable opportunities for advanced soft actuators across various domains, including academia, industry, and everyday life.

(Article source: Tsinghua University, Advanced Materials journal, with adaptations)