Polymer-dispersed liquid crystal elastomers

Rešetič, Andraž; Milavec, Jerneja; Zupančič, Borut; Domenici, Valentina; Zalar, Boštjan

doi:10.1038/ncomms13140

Cited by 67 publications

(46 citation statements)

References 48 publications

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“…Therefore the LC polymer particles act as microscopic photoactuators whose operation can be potentially amplified and transduced across increasing length scales providing a versatile tool for state‐of‐the‐art soft‐robotics . Being inspired by the fact that particles generate mechanical forces and by previously reported concept of polymer‐dispersed liquid crystal elastomers we have designed polymer actuators controllable by light. The photoactuator is composed from the 50 µm thick film of polydimethylsiloxane (PDMS) coated with the composite layer (≈40 µm) containing shape‐morphing PAAzo microparticles (Figure c, left panel).…”

Section: Resultsmentioning

confidence: 99%

Photocontrollable Deformations of Polymer Particles in Elastic Matrix

Ryabchun

Bobrovsky

2019

Advanced Optical Materials

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into mechanical motion or work, such as photoactuation. [1][2][3][4][5] The funda mental importance of these phenomena occurring under the action of light, such as photofluidization, [6][7][8][9][10][11] photoimmo bilization, [6,12,13] formation of surface relief gratings, [14][15][16][17] and other complex 3D structures [10,[18][19][20][21][22][23][24] can help to develop photo responsive materials for versatile applications and will also improve and extend our knowledge in soft matter.The most extensively studied photo active materials usually contain azoben zene moieties as the lightresponsive unit. The properties of azobenzene such as high quantum yield and reversibility of E-Z photoisomerization, high fatigue resis tance, and large changes in molecular shape and dipole moment upon isomerization make it uniquely suitable as an active unit. Molecular shape changes of azobenzene can be harnessed on a macroscopic level by the embedding active molecules into hierarchically organized matter [25] and by confinement of the photoactive material in space, such as, spherical colloids which can selfassemble into 2D and 3D structures (photonic crys tals). The preparation and study of spherical micrometersized particles based on azobenzene polymers have been reported in a number of recent works revealing the importance for various optical microdevices, photonics, microfluidics, etc. [26][27][28][29][30][31][32][33][34][35][36][37][38] It has been demonstrated that polarized light irradiation results in elongation of these particles along the light polarization. Despite the interest to the research area, several issues like the mechanism and reversibility of microscopic shape changes are still elusive. Moreover, there are no reports on the influence of liquid crystal line (LC) ordering on the shapeshifting and optical properties of the particles, as well as the operation of microparticles has never been exploited to build materials with macroscopic functionalities.In the current work, we have developed a novel elastic composite material containing shapereconfigurable parti cles based on liquid crystalline polymer. We have used sty rene-ethylene-butylene-styrene triblock copolymer (SEBS, Figure 1a) as the elastic matrix which provides large deforma tion and low mechanical stiffness [39] and does not interfere to the deformation of embedded particles. Another important role of the matrix is its elasticity responsible for the compres sive forces experienced by the deformed particles which makes possible the shape to recover. The particles are made of liquid crystal copolymer PAAzo bearing mesogenic and azobenzene One of the key challenges of material science currently is the design of multifunctional "smart" materials combining features from both molecular and supramolecular levels. Pursuing the strategy of amplification and transduction of light-induced motion of small molecules (photoswitches) across increasing length scales to macroscopic level, a novel polymer composite based on shapereconfigurable microparticles is desig...

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Section: Resultsmentioning

confidence: 99%

Photocontrollable Deformations of Polymer Particles in Elastic Matrix

Ryabchun

Bobrovsky

2019

Advanced Optical Materials

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“…Researchers have found out that aligned polymers, such as liquid crystal polymers, can improve the driving performance of photo-isomers. In addition, the combination of the entropy, the elasticity of polymers and the photo-isomerism of azobenzene is beneficial for obtaining potential artificial muscles with a large range of reversible deformation [ 98 , 99 ].…”

Section: Applications Of Shape-memory Polymeric Artificial Musclesmentioning

confidence: 99%

Shape-Memory Polymeric Artificial Muscles: Mechanisms, Applications and Challenges

Chen

Rehman

et al. 2020

Molecules

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Shape-memory materials are smart materials that can remember an original shape and return to their unique state from a deformed secondary shape in the presence of an appropriate stimulus. This property allows these materials to be used as shape-memory artificial muscles, which form a subclass of artificial muscles. The shape-memory artificial muscles are fabricated from shape-memory polymers (SMPs) by twist insertion, shape fixation via Tm or Tg, or by liquid crystal elastomers (LCEs). The prepared SMP artificial muscles can be used in a wide range of applications, from biomimetic and soft robotics to actuators, because they can be operated without sophisticated linkage design and can achieve complex final shapes. Recently, significant achievements have been made in fabrication, modelling, and manipulation of SMP-based artificial muscles. This paper presents a review of the recent progress in shape-memory polymer-based artificial muscles. Here we focus on the mechanisms of SMPs, applications of SMPs as artificial muscles, and the challenges they face concerning actuation. While shape-memory behavior has been demonstrated in several stimulated environments, our focus is on thermal-, photo-, and electrical-actuated SMP artificial muscles.

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“…However, new promising mechanisms based on photo-actuation, magneto-actuation, and “Joule”-heating electrically driven actuation were observed and are described in this review, taking into account very recent works [107,108,109,110,111,112]. Future developments of these polymer composite materials will probably expand to the field of biological applications and biomimetics [65,113,114,115,116], optical tunable gratings [117,118,119], three-dimensional (3D) printing and 3D morphing technologies [20,32,120,121,122], and flexible stretchable electrodes [123,124].…”

Section: General Conclusion and Perspectivesmentioning

confidence: 99%

“…As reported in several books and reviews [5,6,7,8,9,10,11,12,13], the interplay between the elasticity of the polymer network and the spontaneous orientational ordering of the liquid-crystalline units results in a reversible thermo-mechanical response, as first predicted by de Gennes in 1975 [14] (Scheme 1b). Several synthetic strategies were developed in order to obtain macroscopically aligned LCE samples [6,15,16,17,18,19,20]. The preparation of macroscopically aligned LCEs, associated with a relatively homogeneous orientational order ( S ) of the local nematic (or smectic) domains, is indeed a fundamental feature for their peculiar physical properties, such as the macroscopic, controllable, and reversible shape changes [21].…”

Section: Introductionmentioning

confidence: 99%

Nanostructured Composites Based on Liquid-Crystalline Elastomers

et al. 2018

Self Cite

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Liquid-crystalline elastomers (LCEs) are the object of many research investigations due to their reversible and controllable shape deformations, and their high potential for use in the field of soft robots and artificial muscles. This review focuses on recent studies about polymer composites based on LCEs and nanomaterials having different chemistry and morphology, with the aim of instilling new physical properties into LCEs. The synthesis, physico-chemical characterization, actuation properties, and applications of LCE-based composites reported in the literature are reviewed. Several cases are discussed: (1) the addition of various carbon nanomaterials to LCEs, from carbon black to carbon nanotubes, to the recent attempts to include graphene layers to enhance the thermo-mechanic properties of LCEs; (2) the use of various types of nanoparticles, such as ferroelectric ceramics, gold nanoparticles, conductive molybdenum-oxide nanowires, and magnetic iron-oxide nanoparticles, to induce electro-actuation, magnetic-actuation, or photo-actuation into the LCE-based composites; (3) the deposition on LCE surfaces of thin layers of conductive materials (i.e., conductive polymers and gold nanolayers) to produce bending actuation by applying on/off voltage cycles or surface-wrinkling phenomena in view of tunable optical applications. Some future perspectives of this field of soft materials conclude the review.

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Polymer-dispersed liquid crystal elastomers

Cited by 67 publications

References 48 publications

Photocontrollable Deformations of Polymer Particles in Elastic Matrix

Photocontrollable Deformations of Polymer Particles in Elastic Matrix

Shape-Memory Polymeric Artificial Muscles: Mechanisms, Applications and Challenges

Nanostructured Composites Based on Liquid-Crystalline Elastomers

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