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Characterizations of the abnormal phase. a) Chemical compositions of LCEs that could not grow. b) POM images of the freshly prepared sample under crossed polarizer and analyzer in the first heating–cooling cycle. Scale bars: 500 µm. c) WAXS results of the elastomer in different states. d) POM images of the annealed white sample under crossed polarizer and analyzer upon heating. The birefringence change was contrary to that of normal liquid crystal behavior. Scale bars: 200 µm.
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It is common knowledge that when an elastomer (rubber) is stretched, its length will maintain if its two ends are fixed. Here, we serendipitously find that an elastomer slowly elongated further to achieve buckling under such conditions, whose final length is much longer than the pre‐stretched length. This allows to design untethered autonomous synt...
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Soft robots offer a myriad of potential because of their intrinsically compliant bodies, enabling safe interactions with humans and adaptability to unpredictable environments. However, most of them have limited actuation speeds, require complex control systems, and lack sensing capabilities. To address these challenges, herein, a class of metacaps...
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... [18,[20][21][22][23][24] However, if the birefringence comes from dynamic molecular assemblies, the birefringence would become more complicated, since it is hard to generate exactly the same orientation, size, and geometry of self-assembled domains. [25][26][27][28] This inspires that such birefringence is in high analogy to the pattern of Jun Porcelain, which is probably possible to be employed to create unduplicable anticounterfeiting techniques. ...
Information security is of predominant significance, while multiple logic information encryption techniques remain challenging. Here it is reported that upon coupling the unduplicable Jun Porcelain‐like birefringence and it enables polarized fluorescence with solid phase molecular self‐assembly(SPMSA), multiple logic information encryption can be achieved upon correctly applying UV light and polarizing angles. Since each birefringence is unique and can be transformed into a corresponding digital bar code, the multiple logic can be further encrypted with the assistance of a digital bar code bank, thus yielding the ultimate information security.
... In soft robotics, new concepts for continuously growing links (robot axes) are being studied, but these approaches primarily manipulate geometric dimensions and are mostly irreversible [15,16]. Other relevant technical properties for production machines remain unadaptable, and using polymer materials results in insufficient basic technical properties. ...
The increasing volatility of the markets and the growing demand for customized products are challenges for future production to ensure maximum flexibility and adaptability. This paper introduces software-defined value stream process systems (SVPSs), a novel approach that extends the concept of software-defined manufacturing into autonomous, reconfigurable production systems. SVPSs establish a cyber–physical chain that links product features to requirements, enabling their fulfillment through modular machine and process hardware. A modular construction kit of individually combinable hardware and associated software modules is presented. These modules are coordinated via a digital process chain that enables holistic simulations, optimizations, and planning based on a Digital Twin. This system is based on software-defined manufacturing but extends it into autonomous reconfigurable machines. By enabling virtual planning and commissioning of entire production lines, the SVPS concept provides an efficient and adaptable solution to meet the demands of volatile markets.
... The pioneering researches about the energy-dissipation behaviors of LCNs were conducted by Terentjev et al., who firstly reported the siloxane backbone-based side-chain LCNs as potential dissipation materials and demonstrated the power law dependence of modulus and frequency within side-chain LCN materials 11,12 . In 2015, a feasible main-chain LCN fabrication method based on thiol-acrylate Michael addition was developed by Bowman et al. and researches about the main-chain LCN system have become a hotspot subsequently [16][17][18][19][20][21] . The main-chain LCNs showed a superior performance in attenuating vibration and damping impact than commercial damping materials 10,22,23 . ...
... We chose the main-chain LCN based on thiol-acrylate Michael addition as the soft LCN matrix, which has been widely used as energydissipation materials in a number of researches 16,21,30 . In consideration of the compatibility between c-LCP and LCN, the mesogenic moieties of c-LCP and LCN should be similar. ...
Liquid crystal networks (LCN) have attracted surging interest as extraordinary energy-dissipation materials owning to their unique dissipation mechanism based on the re-orientation of mesogens. However, how to integrate high Young’s modulus, good dissipation efficiency and wide effective damping temperature range in energy-dissipation LCN remains a challenge. Here, we report a strategy to resolve this challenge by fabricating robust energy-dissipation liquid crystal semi-interpenetrating polymer network (LC-semi-IPN) consisting crystalline LC polymers (c-LCP). LC-semi-IPN demonstrates a superior synergistic performance in both mechanical and energy-dissipation properties, surpassing all currently reported LCNs. The crystallinity of c-LCP endows LC-semi-IPN with a substantial leap in Young’s modulus (1800% higher than single network). The chain reptation of c-LCP also promotes an enhanced dissipation efficiency of LC-semi-IPN by 200%. Moreover, its effective damping temperature reaches up to 130 °C, which is the widest reported for LCNs. By leveraging its exceptional synergistic performance, LC-semi-IPN can be further utilized as a functional architected structure with exceptional energy-dissipation density and deformation-resistance.
... Even until recently, there is only one shape-shifting polymer that has realized spontaneous self-growth 11 . The material belongs to liquid crystal elastomers (LCEs), which are outstanding shape-shifting polymers due to their large actuation strain and muscle-like energy density 12,13 . ...
... Normal LCE actuation is based on the liquid crystal-isotropic phase transition, which generally requires external stimuli 14 . Different from LCE actuations, the self-growth is a rare phenomenon that is observed only in the specific LCE system in our previous work 11 . The self-growing LCEs can independently and spontaneously grow to an extended length beyond the original length at room temperature without external stimuli or energy input, based on the transformation from an unstable state to a stable state 11 . ...
... Different from LCE actuations, the self-growth is a rare phenomenon that is observed only in the specific LCE system in our previous work 11 . The self-growing LCEs can independently and spontaneously grow to an extended length beyond the original length at room temperature without external stimuli or energy input, based on the transformation from an unstable state to a stable state 11 . Despite all these advantages, the self-growth has strict requirements for LCE samples. ...
To date, only one polymer can self-grow to an extended length beyond its original size at room temperature without external stimuli or energy input. This breakthrough paves the way for significant advancements in untethered autonomous soft robotics, eliminating the need for the energy input or external stimuli required by all existing soft robotics systems. However, only freshly prepared samples in an initial state can self-grow, while non-fresh ones cannot. The necessity of synthesizing from monomers for each use imposes significant limitations on practical applications. Here, we propose a strategy to rejuvenate non-fresh samples to their initial state for on-demand self-growth through the synergistic effects of solvents and dynamic covalent bonds during swelling. The solvent used for swelling physically transforms the non-fresh LCEs from the liquid crystal phase to the isotropic phase. Simultaneously, the introduction of the transesterification catalyst through swelling facilitates topological rearrangements through exchange reactions of dynamic covalent bonds. The rejuvenation process can also erase growth history, be repeated several times, and be regulated by selective swelling. This strategy provides a post-modulation method for the rejuvenation and reuse of self-growing LCEs, promising to offer high-performance materials for cutting-edge soft growing robotics.
... Fourier transform infrared (FTIR) spectroscopy of the film before and after UV irradiation was measured to prove the success of photo-cross-linking. The reduction of characteristic peaks (C�C stretch at 1642 cm −1 , �C−H stretch at 3052 cm −1 , and S−H stretch at 2570 cm −1 ) suggests a click reaction between the sulfhydryl group and double bond under UV light, 16,24 indicating successful cross-linking ( Figure S3). The gel contents of polymer films with different UV irradiation times (t ir ) were measured by the solvent extraction method to explore the impact of t ir on cross-linking. Figure 2a shows that the gel content increased from 70% to 90% with the extension of t ir from 15 to 90 s, indicating an improvement in ρ c . ...
... [14] The exchange reaction of dynamic covalent bonds that occurs at ambient temperatures contributes to the permanent orientation ( Figure 2c). The LCE has been proven to be vitrimers, [15] a type of permanently crosslinked covalent adaptable networks capable of rearranging their network topology through exchange reactions. [16] Our recent study has revealed the intrinsic transesterification in this LCE system, wherein the ester groups in PETMP and RM257 played a previously unrecognized role in fine-tuning the topological structure of networks. ...
... [16] Our recent study has revealed the intrinsic transesterification in this LCE system, wherein the ester groups in PETMP and RM257 played a previously unrecognized role in fine-tuning the topological structure of networks. [15] Here, nTBD effectively promoted transesterification as an alkaline catalyst. [10] Consistent with covalent adaptable networks, larger actuation ratios were observed with higher catalyst additions and longer processing time (Figure 4a). ...
... [10] Consistent with covalent adaptable networks, larger actuation ratios were observed with higher catalyst additions and longer processing time (Figure 4a). LCE without nTBD also showed increasing actuation strain over time since dipropylamine (DPA) used for crosslinking also has the capability to catalyze transesterification. [15,17] However, as DPA was volatile and the LCEs were dried at 80°C, there was little residual DPA after drying. Consequently, the actuation strain of LCE without nTBD was significantly lower than that of the samples catalyzed by nTBD. ...
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. 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. Due to the hysteretic behavior, the LCEs (resemble “cloth”) effectively retain predefined shapes after stretching and releasing for extended periods. Subsequently, the samples naturally become soft actuators (resemble “clothes”) via the exchange reaction at ambient temperatures. 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.
... After the orientation of LCE-HUB is completed, there will be an increase in length along the orientation direction, which has been reported in previous studies. [54] Therefore, the obtained bilayer film has a curved shape, as shown in Figure S19a (Supporting Information). The interface of the bilayer film was scanned using SEM, and it was shown that the interface part had been integrated into a whole, as shown in Figure S19b (Supporting Information). ...
Recently, researchers have been exploring the use of dynamic covalent bonds (DCBs) in the construction of exchangeable liquid crystal elastomers (LCEs) for biomimetic actuators and devices. However, a significant challenge remains in achieving LCEs with both excellent dynamic properties and superior mechanical strength and stability. In this study, a diacrylate‐functionalized monomer containing dynamic hindered urea bonds (DA‐HUB) is employed to prepare exchangeable LCEs through a self‐catalytic Michael addition reaction. By incorporating DA‐HUB, the LCE system benefits from DCBs and hydrogen bonding, leading to materials with high mechanical strength and a range of dynamic properties such as programmability, self‐healing, and recyclability. Leveraging these characteristics, bilayer LCE actuators with controlled reversible thermal deformation and outstanding dimensional stability are successfully fabricated using a simple welding method. Moreover, a biomimetic triangular plum, inspired by the blooming of flowers, is created to showcase reversible color and shape changes triggered by light and heat. This innovative approach opens new possibilities for the development of biomimetic and smart actuators and devices with multiple functionalities.
... 40 Liang et al. developed an elastomer that could grow automatically without the need for external stimuli after pre-strain has been installed. 65 When growth starts, it will keep going even after the force is removed. Very few materials can undergo such behavior, and those that do show an unusual liquid crystal phase. ...
... Current results for these LCEs are limited; however, once growth speeds in the material can be controlled, multiple self-elongating LCEs can be assembled into complex actuators with low energy requirements. 65 Overall, elastomer actuators are expected to play a major role in soft robotics in the future. ...
Rubbers and elastomers have a rich history that spans many eras of human civilization dating back to 1600 A.D. Upon their introduction into Europe, they became common materials in shoes and fabrics. With the invention of vulcanization by Charles Goodyear in 1839, rubbers became widely used in many new applications, ranging from tires to industrial machine parts. Today, rubbers and elastomers are essential in the development of innovative, emerging technologies. This review exemplifies how rubbers and elastomers have been used to advance the emerging fields of soft robotics through soft grippers and dielectric elastomer actuators, stretchable and wearable devices through conductive elastomers and smart elastomers used in thermal camouflage and sensors, biomedical applications through tissue scaffolding and stretch triggered drug delivery, and energy harvesting through piezoelectric elastomers and wave harvesting triboelectric nanogenerators. This paper also briefly summarizes other developments in these fields, as well as glimpses into other emerging fields that are advancing through the incorporation of rubbers and elastomers.
... This is illustrated, for instance, by the fascinating color change of chameleons, [9] the transformation of shape and color of zebrafish, [10] and the petiole sagging observed with the mimosa plant. [11] Smart structures ranging from relatively soft materials such as elastomers, [12] liquid crystals, [13] and hydrogels [14] to stiffer materials such as carbon-based materials [15] have been previously reported and suggested for applications in smart sensors, optoelectronic devices, memories, and advanced drug delivery protocols. [16,17] One exceptional class of soft materials that has been greatly overlooked in the past is organic crystals, a class of materials that are yet to claim their position in the global materials space as lightweight and dense emissive media. ...
Organic single crystals quickly emerge as dense yet light and nearly defect‐free media for emissive elements. Integration of functionalities and control over the emissive properties is currently being explored for a wide range of these materials to benchmark their performance against organic emissive materials diluted in powders or films. Here, we report mechanically flexible emissive chiral organic crystals capable of an unprecedented combination of fast, reversible, and low‐fatigue responses. UV‐excited single crystals of both enantiomers of the material, 4‐chloro‐2‐(((1‐phenylidene)imino)methyl)phenol, exhibit a drastic yet reversible change in the emission color from green to orange‐yellow within a second and can be cycled at least 2000 times. The photoresponse was found to depend strongly on the excitation intensity and temperature. Combining chirality, mechanical compliance, rapid emission switching, multiple responses, and writability by UV light, this material provides a unique and versatile platform for developing organic crystal‐based materials for on‐demand signal transfer, information storage, and cryptography.
