Extremely Soft, Conductive, and Transparent Ionic Gels by 3D Optical Printing

Ahmed, Kumkum; Naga, Naofumi; Kawakami, Masaru; Furukawa, Hidemitsu

doi:10.1002/macp.201800216

Cited by 31 publications

(28 citation statements)

References 36 publications

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“…Technol. 2019, 4,1900071 Figure 1d), which correspond to crystal lattice spacings of 0.412, 0.414, and 0.435 nm, respectively. This diffraction can be attributed to the crystalline state formed by the long alkyl side chain of SA.…”

Section: Chemical and Structural Propertiesmentioning

confidence: 99%

“…[1][2][3][4] However, most of these materials resulted in printed objects that are inanimate or dead, restricting their applications in conditions where time evolving shape transformation is required. [1][2][3][4] However, most of these materials resulted in printed objects that are inanimate or dead, restricting their applications in conditions where time evolving shape transformation is required.…”

Section: Introductionmentioning

confidence: 99%

“…In recent years, a wide variety of advanced and soft materials with different functionalities have been developed for 3D printing to fabricate complex designs using a moldless and smart technique. [1][2][3][4] However, most of these materials resulted in printed objects that are inanimate or dead, restricting their applications in conditions where time evolving shape transformation is required. Through the development of printing precursors with the functional potential of smart materials, examples of hydrogel-based 4D printing include 3D printed NIPAM-based thermosensitive smart valves reported by Bakarich et al [28] and biomimetic acrylamide/NIPAM-based 4D printing stimulated by anisotropic swelling of hydrogel composites with cellulose fibrils realized by Galdman et al [29] Despite substantial advancements, printable responsive and active materials for soft actuators are inadequate.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

4D Printing of Shape‐Memory Hydrogels for Soft‐Robotic Functions

Shiblee

Ahmed

Kawakami

et al. 2019

Adv Materials Technologies

Self Cite

154

111

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a new active dimension of "time" has evolved, leading to the new concept of 4D printing, which refers to the ability of 3D printed structures to actively transform over time in response to environmental stimuli. [5] Smart or stimuliresponsive materials have the unique ability to return from a temporary deformed state, induced by heat, light, pH, ultrasound, chemical substances, [6][7][8][9][10][11][12][13] etc., to their permanent, i.e., original, shape, thus exhibiting advantages for applications in numerous sectors, such as sensors and actuators, [14] tissue engineering, [15] bio-separation devices, and controlled drug delivery. [16][17][18][19][20][21] To date, two main types of materials have been considered to realize 4D printing: shape memory polymers (SMPs) and hydrogels. SMP-based 4D printing offers structural modification and recovery in response to temperature, which are established through complex functionalities of multiple or reversible shape switching, and such printing may provide inspiration for the molecular architecture of shape memory hydrogels (SMHs). However, SMPs cannot completely replace hydrophilic soft materials due to the limitations arising from their sustainability in wet environments, rigidity, material permeability, and biological compatibility. [22] Therefore, mechanically active, self-shaping hydrogels that undergo desired, programmable 3D shape transformations and execute mechanical tasks as soft robots under an external trigger have recently attracted growing interest. The use of a hydrogel system in soft robotic counterparts offers distinct advantages: simple designs, low cost, processability at low temperatures and in aqueous environments, and the possibility to mimic human functionality. [23,24] Directed movement of hydrogels can be obtained by expansion/contraction, for example, by isotropic volume expansion or shrinkage of homogeneous hydrogels or by the bending/unbending approach, which represents an anisotropic deformation and often involves fabrication of a hydrogel structure with two layers with different swellability values. [25][26][27][28][29] The first hydrogel-based bilayer actuation system composed of pNIPAM and acrylamide, obtained through conventional mold techniques, was demonstrated by Hu et al.; [25] after that, a range of self-assembled, origami-inspired structures were reported, [27,[30][31][32][33][34][35][36][37][38] but only a few works successfully realized 4D printing with hydrogels. [28,29] Some noteworthy Hydrogel actuators with soft-robotic functions and biomimetic advanced materials with facile and programmable fabrication processes remain scarce. A novel approach to fabricating a shape-memory-hydrogel-(SMG)-based bilayer system using 3D printing to yield a soft actuator responsive to the methodical application of swelling and heat is introduced. Each layer of the bilayer is composed of poly(N,N-dimethyl acrylamide-co-stearyl acrylate) (P(DMAAm-co-SA))-based hydrogels with different concentrations of the crystalline monomer SA within the SMG network...

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Section: Chemical and Structural Propertiesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

4D Printing of Shape‐Memory Hydrogels for Soft‐Robotic Functions

Shiblee

Ahmed

Kawakami

et al. 2019

Adv Materials Technologies

Self Cite

154

111

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Section: Ionic Electroactive Polymersmentioning

confidence: 99%

Materials as Machines

2020

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of responsive materials as machines is in robotics. The vision, leadership, and research of Bar-Cohen is seminal in both invigorating and focusing current-day research activities to develop responsive materials [2] and implement [3] them as lightweight, dexterous, and gentle (e.g., soft) robotic elements. In this spirit, this review exhaustively details the materials, the nature of their stimuli-response, and discusses considerations for their implementation in robotic systems and subsystems.Robotics is a well-established but growing field of research. Sustained progress in both performance and functionality continue to be realized in commercial robotic systems largely based on conventional materials and their integration with mechanisms. A recent example is the Atlas robot from Boston Dynamics [4] (Figure 1a). The incorporation of stimuli-responsive materials in robotics has largely focused on component-level demonstrations to extend the performance of a subsystem (such as a hand or gripper).Stimuli-responsive materials, spanning nearly all classes of materials and size scales, are currently subject to widespread examination in corporate, government, and academic research laboratories (Figure 1b-d). [5][6][7] In some cases, these materials have already found widespread commercial implementation in end use and are comparatively mature. The materials and fundamentals of their responses are summarized in Figure 2. Shape memory alloys (SMAs) and ceramic piezoelectric materials are distinctive in that they are hard, stimuli-responsive materials. Deformation of these materials can produce large energy densities due to their inherent stiffness. Electroactive polymers (EAPs) remain a topic of considerable interest, particularly dielectric elastomer actuators (DEAs). Engineered systems are rapidly emerging and enabling performance gains in robotics, largely based on pneumatic or fluidic (such as HASEL [8] actuators) transport processes that localize deformation to generate force or produce motion. Soft materials, such as shape memory polymers (SMPs), hydrogels, and liquid crystalline polymer networks (LCNs) and elastomers (LCEs) may offer distinctive functional performance to robotic systems in allowing local control of deformation without the need for complex interfacing with mechanisms. As will be evident, each of these materials has inherent advantages and performance tradeoffs that must be considered in functional implementations. However, responsive material systems have a common obstacle to widespread use: the performance and Machines are systems that harness input power to extend or advance function. Fundamentally, machines are based on the integration of materials with mechanisms to accomplish tasks-such as generating motion or lifting an object. An emerging research paradigm is the design, synthesis, and integration of responsive materials within or as machines. Herein, a particular focus is the integration of responsive materials to enable robotic (machine) functions such as gripping, lifting, or motility (walk...

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“…Transparent elastomers can be applied to contact lenses, flexible couplings, wearable electronics, sensing, etc., but the balance between mechanical properties and light transmission, and healing effects still faces great challenges. Polymethyl methacrylate (PMMA) is often used as a transparent material due to its excellent light transmittance.…”

Section: Introductionmentioning

confidence: 99%

Robust, Transparent, Thermally Healable Copolyacrylate Elastomer: The Effect of β‐Hydroxyethyl Acrylate on its Properties

Zhao

Chen

Dai

et al. 2019

Macro Chemistry & Physics

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as the hard segment phase. Montana et al. [14] discovered that the block copolymer PMMA-PBA-PMMA could toughen PMMA up to an elongation at break about 17.5%, but decrease its tensile strength. It can be seen from the above-mentioned literatures that the toughness of PMMA can be greatly improved by introducing inorganic nanofillers, polymers with lower T g , or copolymerization units. However, the methods can cause relatively low strength of polyacrylate, and reduce its transparency at visible light deriving from the presence of phase separation structure. The incorporation of the third or more monomer units into binary polyacrylate can increase the compatibility of original polymers, that is, a narrower T g gap between the soft and hard phases, [16] thereby changing the phase separation structure. [17,18] The particle-brush and star polymers with the core-shell structure are prepared by atom transfer radical polymerization of BA with styrene and acrylonitrile, and then blended with PMMA. [19] The toughness of the blend prepared is better than PMMA, and its transparency is close to that of PMMA. The polymer films prepared by methyl methacrylate, butyl methacrylate, and glycidyl methacrylate exhibit different T g s with the increase of glycidyl methacrylate content, so the phase separation structure was modified and the latex film cast on the glass plate was transparent. [20] It can be seen that the copolyacrylate is still an elastomer and has good visible-light transmittance after the incorporation of the third or more monomer units.The transmittance of elastomer will be significantly reduced after damage, while the self-healing of transparent elastomer can improve its application performance and service life. The self-healing effect derived from dynamic non-covalent interactions, such as hydrogen bonding, [21][22][23] electrostatic, [7] dipoledipole, [3] host-guest, [24,25] intermolecular interactions, [26,27] and so on, can be applied to the transparent elastomer. The copolyacrylate is still an elastomer after the incorporation of the third or more monomer units, which will provide the mobility of molecular chain and contribute to intermolecular interactions, promoting self-healing, but will decrease the mechanical strength of copolyacrylate. So the healing of transparent copolyacrylate elastomer remains to be further studied. [28,29] The copolymerization of BA and MMA can improve the toughness of PMMA, but its transparency is reduced by the phase separation behavior. The glass transition temperature of HEA homopolymer is between those of PMMA and PBA. HEA will be incorporated into the copolymerization system as a third Transparent ElastomersThe contradiction between mechanical properties, transparency, and healing effects for polyacrylate elastomers is not solved yet. The copolyacrylate elastomers are prepared based on the bulk copolymerization with methyl methacrylate (MMA) and butyl acrylate (BA), incorporating the β-hydroxyethyl acrylate (HEA) monomer. Compared with PMMA-co-PBA, with the incorporation of HEA...

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Extremely Soft, Conductive, and Transparent Ionic Gels by 3D Optical Printing

Cited by 31 publications

References 36 publications

4D Printing of Shape‐Memory Hydrogels for Soft‐Robotic Functions

4D Printing of Shape‐Memory Hydrogels for Soft‐Robotic Functions

Materials as Machines

Robust, Transparent, Thermally Healable Copolyacrylate Elastomer: The Effect of β‐Hydroxyethyl Acrylate on its Properties

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