Photo‐Induced Anomalous Deformation of Poly(<i>N</i>‐Isopropylacrylamide) Gel Hybridized with an Inorganic Nanosheet Liquid Crystal Aligned by Electric Field

Inadomi, Takumi; Ikeda, Shogo; Okumura, Yasushi; Kikuchi, Hirotsugu; Miyamoto, Nobuyoshi

doi:10.1002/marc.201400333

Cited by 68 publications

(56 citation statements)

References 28 publications

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“…[77][78][79] In recent work, Inadomi et al prepared hydrogel films that were doped with uniaxially ordered liquid crystalline nanosheets that had adsorbed a dye (Figure 4c). [80] In top-and side-images of the ordered nanocomposite hydrogel, uniform interference colors of blue or yellow were observed, which demonstrated that the liquid crystalline nanosheets were aligned along the applied electric field. In addition, their hydrogel showed not only anisotropic shrinkage but also anomalous expansion in a specific direction; this behavior contrasted with that of the conventional composite hydrogel with unordered structure, which only showed isotropic swelling/deswelling that was induced by heat.…”

Section: Electric Fieldsmentioning

confidence: 96%

Bioinspired Nanocomposite Hydrogels with Highly Ordered Structures

et al. 2017

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In the human body, many soft tissues with hierarchically ordered composite structures, such as cartilage, skeletal muscle, the corneas, and blood vessels, exhibit highly anisotropic mechanical strength and functionality to adapt to complex environments. In artificial soft materials, hydrogels are analogous to these biological soft tissues due to their “soft and wet” properties, their biocompatibility, and their elastic performance. However, conventional hydrogel materials with unordered homogeneous structures inevitably lack high mechanical properties and anisotropic functional performances; thus, their further application is limited. Inspired by biological soft tissues with well‐ordered structures, researchers have increasingly investigated highly ordered nanocomposite hydrogels as functional biological engineering soft materials with unique mechanical, optical, and biological properties. These hydrogels incorporate long‐range ordered nanocomposite structures within hydrogel network matrixes. Here, the critical design criteria and the state‐of‐the‐art fabrication strategies of nanocomposite hydrogels with highly ordered structures are systemically reviewed. Then, recent progress in applications in the fields of soft actuators, tissue engineering, and sensors is highlighted. The future development and prospective application of highly ordered nanocomposite hydrogels are also discussed.

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Section: Electric Fieldsmentioning

confidence: 96%

Bioinspired Nanocomposite Hydrogels with Highly Ordered Structures

et al. 2017

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“…In particular,m icropatterned electrodes enable the precise positioning of oriented nanofillers in thin hydrogel films to afford hierarchical structures that are generally difficult to access by other methods.Itshould be noted that electric fields possibly cause undesired electrochemical decomposition and electrophoresis.T oa void these problems,t he conditions,s uch as voltage, current frequency, and sample thickness,o ften need to be optimized. Thus far, electric orientation has been used for the synthesis of anisotropic hydrogels containing functionalized carbon nanotubes, [42][43][44] clay nanosheets, [45,46] silver nanowires, [47] silk nanofibers, [48] and barium titanate particles. [49] Similar to electric fields,m agnetic fields can be used to afford anisotropic hydrogels,w here an anofiller is oriented with its easy magnetization axis parallel or antiparallel to the applied magnetic field (Figure 2b).…”

Section: Hydrogels With Oriented Nanofillersmentioning

confidence: 99%

“…[18,[88][89][90][91] Ty pically,a na queous solution of an anionic polymer is filled in ac ontainer, and one end of the container is put in contacted with an aqueous solution containing multivalent cations so that the cationic ions diffuse directionally.A st he diffusion proceeds,t he anionic polymer chains are crosslinked anisotropically to afford ah ydrogel with an oriented polymer-chain network. Va rious anionic polymers have been used as components of such networks, shear forces collagen nanofibers [23] cellulose nanofibers [24] lamellar bilayer [25][26][27] imogolite nanotubes [33] graphene oxide [34] clay nanosheets [32] graphene oxide [34] -s ynthetic peptide nanofibers [19,20] collagen nanofibers [21,23] electric fields silk nanofibers [48] clay nanosheets [46] -f unctionalized carbon nanotubes [42][43][44] silk nanofibers [48] magnetic fields barium ferrite particles [53,55] graphene oxide [70] titanate nanosheets [71] alumina platelets [60] titanate nanosheets [72] magnetite particles [52] micelles [66,67] -Section 2.2 Hydrogels with oriented polymerchain networks compression or stretching alginate/acrylic polymer [81] acrylic polymer [82] poly(vinyl alcohol) [84,85] -s cleroglucan [87] poly(vinyl alcohol) [80] collagen nanofibers…”

Section: Hydrogels With Oriented Polymer-chain Networkmentioning

confidence: 99%

“…As an extension of this study,the same group developed ap hotoresponsive version by doping as imilar hydrogel with an organic dye for photothermal conversion. [46] To realize am ore complicated deformation, combining abimorph structure and an anisotropic microstructure is quite an effective approach, as demonstrated by Studart and coworkers (Figure 4c). [60] They used strips of cellulose-or PNIPA-based hydrogels that contained magnetically oriented alumina platelets as the components of the bimorphs (Section 2.1).…”

Section: Anisotropic Actuationmentioning

confidence: 99%

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Synthesis of Anisotropic Hydrogels and Their Applications

2018

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Owing to their water-rich structures, which are similar to those of biological tissues, hydrogels have long been regarded as promising scaffolds for artificial tissues and organs. However, in terms of the structural anisotropy, most synthetic hydrogels are substantially different from biological systems. Synthetic hydrogels are usually composed of randomly oriented three-dimensional polymer networks whereas biological systems adopt anisotropic structures with hierarchically integrated building units. Such anisotropic structures often play essential roles in biological systems to exhibit particular functions. In this context, anisotropic hydrogels provide an entry point for exploring biomimetic applications of hydrogels. Reflecting these aspects, an increasing number of studies on anisotropic hydrogels have been reported recently. This Minireview highlights the use and perspectives of these anisotropic hydrogels, particularly focusing on their preparation, structures, and applications.

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“…In contrast, synthetic hydrogels usually have an isotropic and amorphous structure, resulting in the absence of anisotropic optical and mechanical properties. Inspired by the nature, there are many efforts to develop anisotropic hydrogels by different strategies, including molecular self‐assembly, electric/magnetic field‐directed orientation, and diffusion‐induced orientation, to form ordered structures before or during the gelation process. For instance, Thomas and co‐workers prepared photonic hydrogels by molecular self‐assembly of a block copolymer to form a uniform lamellar structure, which was subsequently fixed by chemical cross‐linking .…”

Section: Introductionmentioning

confidence: 99%

Programmed Diffusion Induces Anisotropic Superstructures in Hydrogels with High Mechano‐Optical Sensitivity

Qiao

Gong

et al. 2019

Adv Materials Technologies

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including low sliding friction and strong bonding to the bone. [2,3] In contrast, synthetic hydrogels usually have an isotropic and amorphous structure, resulting in the absence of anisotropic optical and mechanical properties. Inspired by the nature, there are many efforts to develop anisotropic hydrogels by different strategies, [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20][21] including molecular self-assembly, [5,6] electric/magnetic field-directed orientation, [7][8][9][10][11][12][13][14] and diffusion-induced orientation, [15][16][17] to form ordered structures before or during the gelation process. For instance, Thomas and co-workers prepared photonic hydrogels by molecular self-assembly of a block copolymer to form a uniform lamellar structure, which was subsequently fixed by chemical cross-linking. [5] The resultant hydrogel showed iridescent colors under different ionic strength owing to the Bragg diffraction of the light with a specific wavelength. Aida, Miyamoto, and their coworkers applied magnetic and electric fields to orient the charged nanosheets followed by in situ polymerization of the precursor solution to fabricate monodomain nanocomposite hydrogels, which showed anisotropic optical and mechanical properties, as well as anisotropic actuation under external stimulations. [7][8][9] Dobashi and co-workers have developed anisotropic physical hydrogels by dialyzing the solution of curdlan or DNA in the solution of multivalent metallic ions, in which the diffusion of ions induced molecular orientation and gelation of the negatively charged, rigid biomacromolecules. [15,16] Although big progress has been achieved in designing monodomain hydrogels, it still remains a big challenge to develop anisotropic gels with intricate ordered structures, because of lacking efficient approach to control the local orientation of molecules or nanoparticles at different regions. Recently, Studart and co-workers fabricated composite hydrogels by multistep polymerization with a magnetic field to orient the nanofillers along a specific direction. [22,23] The integrated hydrogels with complex ordered structures showed programmed deformations under external stimulations. However, the fabrication process was time-consuming because the separate domains with specific orientations should be completed step-wisely to form the composite hydrogel. A facile and efficient strategy is really desired to prepare hydrogels with intricate anisotropic superstructures, which is an important step to develop biomimetic materials with versatile functions. A straightforward idea is to simultaneously modulate the external field with independent Most soft biotissues possess intricate anisotropic superstructures, which afford living organism versatile functionalities. However, it remains a big challenge to develop such complex ordered structures in synthetic hydrogels. Here a simple and efficient strategy to fabricate periodically patterned hydrogels with complex anisotropic structures by diffusion-induced orientation and g...

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Photo‐Induced Anomalous Deformation of Poly(N‐Isopropylacrylamide) Gel Hybridized with an Inorganic Nanosheet Liquid Crystal Aligned by Electric Field

Cited by 68 publications

References 28 publications

Bioinspired Nanocomposite Hydrogels with Highly Ordered Structures

Bioinspired Nanocomposite Hydrogels with Highly Ordered Structures

Synthesis of Anisotropic Hydrogels and Their Applications

Programmed Diffusion Induces Anisotropic Superstructures in Hydrogels with High Mechano‐Optical Sensitivity

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