Advances in 4D printing of liquid crystalline elastomers: materials, techniques, and applications

Guan, Zhecun; Bae, Jinhye

doi:10.1039/d2mh00232a

Cited by 79 publications

(66 citation statements)

References 216 publications

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“…[ 24 , 25 , 26 ] A similar approach using thiol‐Michael oligomerization and subsequent photopolymerization of acrylate‐terminated oligomers has been previously used to fabricate LCEs by mechanical alignment and additive manufacturing techniques. [ 12 , 27 , 28 , 29 , 30 , 31 ] In this approach, using dithiols as comonomers enables variation of the spacer length and properties when a thiol‐Michael reaction is used to generate linear chains in the polymer before crosslinking. [ 27 , 32 ] To our knowledge, no prior study has detailed the preparation of LCEs amenable to surface‐enforced alignment based on thiol‐Michael addition reactions.…”

Section: Introductionmentioning

confidence: 99%

Surface‐Enforced Alignment of Reprogrammable Liquid Crystalline Elastomers

et al. 2022

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Liquid crystalline elastomers (LCEs) are stimuli-responsive materials capable of undergoing large deformations. The thermomechanical response of LCEs is attributable to the coupling of polymer network properties and disruption of order between liquid crystalline mesogens. Complex deformations have been realized in LCEs by either programming the nematic director via surface-enforced alignment or localized mechanical deformation in materials incorporating dynamic covalent chemistries. Here, the preparation of LCEs via thiol-Michael addition reaction is reported that are amenable to surface-enforced alignment. Afforded by the thiol-Michael addition reaction, dynamic covalent bonds are uniquely incorporated in chemistries subject to surface-enforce alignment. Accordingly, LCEs prepared with complex director profiles are able to be programmed and reprogrammed by (re)activating the dynamic covalent chemistry to realize distinctive shape transformations.

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Section: Introductionmentioning

confidence: 99%

Surface‐Enforced Alignment of Reprogrammable Liquid Crystalline Elastomers

et al. 2022

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“…Injection is a classic plastic molding technique, which can conveniently prepare polymer fibers with different diameters in a large scale [ 9 , 31 , 34 , 36 ]. Figure 1 (a) shows the fabrication process and morphology of the SLMPFs.…”

Section: Resultsmentioning

confidence: 99%

“…Semiliquid metals (SLMs) with unique properties of tunable rheology [12,17,21,[26][27][28] and metallic conductivity [6,12,[29][30][31][32][33] have been extensively applied in the field of the automotive industry, electronic devices, and aeronautics. With the coexistence of liquid and solid, the fluidity of SLMs can be conveniently mediated by alloy composition and processing conditions based on the classic alloy phase diagram [9,32,[34][35][36]. Therefore, the utilization of SLMs may be a possible way to overcome the phase segregation between the polymers and metals due to the unique tunable rheological features of the liquid-solid structures in SLMs.…”

Section: Introductionmentioning

confidence: 99%

Scalable Fabrication of Metallic Conductive Fibers from Rheological Tunable Semi-Liquid Metals

et al. 2022

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Conductive polymer fibers/wires (CPFs) are important materials in modern technologies due to their unique one-dimension geometry, electrical conductivity, and flexibility. However, the advanced applications of current CPFs are limited by their low electrical conductivities (<500 S/m) and poor interfacial interactions between conductive fillers (e.g., graphite) and polymers. Therefore, in current electrical applications, metal wires/foils like copper and aluminum are the most frequently utilized conductive fibers/wires instead of the inferior conductive CPFs. This work successfully addresses the heavy phase segregation between polymers and conductive inorganic materials to obtain semiliquid metal polymer fibers (SLMPFs) which exhibit an ultrahigh electrical conductivity (over 106 S/m), remarkable thermal processability, and considerable mechanical performance (Young’s modulus: ~300 MPa). Semiliquid metal (gallium-tin alloy) with tunable viscosities is the key to achieve the excellent miscibility between metals and polymers. Both the rheological results and numerical simulations demonstrate the critical viscosity matching for the successful preparation of the fibers. More importantly, the fibers are adapted with classic polymer melt-processing like melt injection, which indicates the scalable production of the highly conductive fibers. The SLMPFs are highly promising substitutes for metal wires/fibers in modern electrical applications such as electricity transmission, data communication, and underwater works.

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“…[18][19][20][21] The extraordinary properties of LCEs, their chemistry and responsiveness to different physical cues, and how they are utilized to enable 4D printing have been extensively discussed in recent reviews. 22,23 We provide herein a succinct review on the physical principles underlying the key methods for LCE molecular programming and recent advances in LC alignment with various additive manufacturing processes to push the boundary of 4D printing. Various applications of additively manufactured LCEs are also highlighted.…”

Section: Introductionmentioning

confidence: 99%

Recent advances in molecular programming of liquid crystal elastomers with additive manufacturing for 4D printing

Wang

Lee

2022

Mol. Syst. Des. Eng.

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Advances in 4D printing of liquid crystalline elastomers: materials, techniques, and applications

Abstract: Liquid crystalline elastomers (LCEs) are polymer networks exhibiting anisotropic liquid crystallinity while maintaining elastomeric properties. Owing to diverse polymeric forms and self-alignment molecular behaviors, LCEs have fascinated state-of-the-art efforts in...

Cited by 79 publications

References 216 publications

Surface‐Enforced Alignment of Reprogrammable Liquid Crystalline Elastomers

Surface‐Enforced Alignment of Reprogrammable Liquid Crystalline Elastomers

Scalable Fabrication of Metallic Conductive Fibers from Rheological Tunable Semi-Liquid Metals

Recent advances in molecular programming of liquid crystal elastomers with additive manufacturing for 4D printing

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