Flow-Orientation of Internal Structure and Anisotropic Properties on Hydrogels Consisted of Imogolite Hollow Nanofibers

Kaneda, Keisuke; Uematsu, Keisuke; Masunaga, Hiroyasu; Tominaga, Yoichi; Shigehara, Kiyotaka; Shikinaka, Kazuhiro

doi:10.2115/fiber.70.137

Cited by 16 publications

(17 citation statements)

References 29 publications

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“…Differently, the elastic modulus in the parallel direction enhanced significantly from 0.35 to 2.12 MPa, indicating that the anisotropic parameter (ratio of modulus in parallel to perpendicular direction) could be adjusted simply by varying the content of nanofibers. It is worth mentioning that the deformed gel exhibited dual higher anisotropic factor and mechanical strength in comparison with most of the reported anisotropic gels (Figure H) …”

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confidence: 64%

Switching between Elasticity and Plasticity by Network Strength Competition

2019

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Switching a material between highly elastic and plastic would be of great use in many fields but has proven to be extremely challenging. Here, the use of mechanical strength competition between two networks in a hybrid material is reported to switch between elasticity and plasticity. In a gel material composed of an elastic polymer network and a shear‐thinning nanofiber network, the excellent elasticity of the gel is demonstrated when the former is stronger than the latter. In contrast, the gel exhibits an extraordinary plasticity, which can be stretched to form a permanent anisotropic and tough gel due to the orientation of the nanofibers. The mechanical strength of each network can be simply tuned by adjusting either the crosslinking density or the loading of the nanofibers. This work may open a window to transform a material between superior elastic and plastic, which is useful for the development of adaptable materials.

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confidence: 64%

Switching between Elasticity and Plasticity by Network Strength Competition

2019

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“…Theorientated structure thus induced is not eternal, but can be converted into an anisotropic hydrogel by in situ polymerization of monomer(s) that are added to the dispersion beforehand ( Figure 1a). [22][23][24][25][26][27][28][29][30][31][32][33][34] Forstructural fixation by hydrogelation, physical aggregation of gelators is also applicable. [19][20][21][35][36][37][38][39][40][41] Owing to its simplicity and easiness,shear-force orientation has been widely used for the synthesis of anisotropic hydrogels containing various types of 1D-or 2D-shaped nanofillers,i ncluding natural [21][22][23] or synthetic [19,20,38,39] peptide nanofibers,c ellulose nanofibers, [24,40,41] surfactant bilayers, [25][26][27][28][29][30][31] and inorganic nanofillers.…”

Section: Hydrogels With Oriented Nanofillersmentioning

confidence: 99%

“…[19][20][21][35][36][37][38][39][40][41] Owing to its simplicity and easiness,shear-force orientation has been widely used for the synthesis of anisotropic hydrogels containing various types of 1D-or 2D-shaped nanofillers,i ncluding natural [21][22][23] or synthetic [19,20,38,39] peptide nanofibers,c ellulose nanofibers, [24,40,41] surfactant bilayers, [25][26][27][28][29][30][31] and inorganic nanofillers. [32][33][34][35][36][37] As al imitation of this method, shear forces cannot be homogeneously applied to thick samples,and the processing occasionally suffers from low reproducibility,particularly when the shear forces are applied manually.…”

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%

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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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“…6 The rst approach is applicable only to materials with adequate electromagnetic properties. The application of mechanical shear however is not dependent on material properties other than its morphology.…”

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confidence: 99%

Alignment of Ge-imogolite nanotubes in isomalt with tunable inter-tube distances

et al. 2017

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aThis study shows the almost perfect alignment of inorganic nanotubes (Ge-imogolite) within polyol filaments. Alignment was obtained by simply cooling a Ge-imogolite-polyol mixture under mechanical stress. Additionally, inter-tube distances in the plane normal to the filaments can be tuned by simply varying the weight fraction of imogolite in the starting solution. The ease of the alignment protocol will stimulate interest for testing new applications which require a good control of the pore density and morphology (periodicity, and high monodispersity of the pore size distribution).Aligning one-dimensional (1D) nanostructures whether organic or inorganic, has recently attracted much attention to develop innovative technological applications.1 Indeed, connement inside nanotubes is likely to enhance existing reactivity or create new properties. For example, permeation rates of gas, water and protons inside carbon nanotubes (CNT) have been shown to exceed by orders of magnitude those observed for other nanopores of similar size.2 The origin of such improved transport properties was attributed to the ordering of the molecules under spatial connement and hydrophobicity of the CNT walls. Remarkable optical properties can also derive from aligned 1D nanostructured objects. As an example, it has been shown that an organized array of CNT can act as a photonic band gap crystal.3 If carbon nanotubes remain the most publicized materials in the literature, much of the focus now shis towards inorganic nanotubes. For example, very large, osmotically induced electric currents generated by salinity gradients were observed inside a single highly charged transmembrane boron nitride nanotube. 4Aligning anisotropic nanostructures oen requires rather involved sample preparation procedures.1 In most cases, the orientation of the nanostructures along a given direction is achieved by applying an external force, such an electromagnetic eld 5 or mechanical shear. 6 The rst approach is applicable only to materials with adequate electromagnetic properties. The application of mechanical shear however is not dependent on material properties other than its morphology. In all cases, the surrounding medium (e.g. solvent) needs to be sufficiently uid to allow the movement of the nanostructures towards a preferential direction. This low viscosity of the matrix will cause the system to relax once the force used to create the alignment is no longer applied. A permanent alignment (outside the force eld) thus requires immobilization of the nanostructures by changing the surrounding matrix and/or its properties.Here we describe the successful alignment of inorganic nanotubes within an organic matrix. The tubes used in the present study were Ge-imogolite, i.e. the Ge analogues of natural imogolite, which are readily obtained by aqueous sol-gel processes with good control over tube length and diameter, wall multiplicity and chemistry; 7-11 the matrix was isomalt, a sugar alcohol used in cooking.The arrangement of the nanotubes within solidied is...

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Flow-Orientation of Internal Structure and Anisotropic Properties on Hydrogels Consisted of Imogolite Hollow Nanofibers

Cited by 16 publications

References 29 publications

Switching between Elasticity and Plasticity by Network Strength Competition

Switching between Elasticity and Plasticity by Network Strength Competition

Synthesis of Anisotropic Hydrogels and Their Applications

Alignment of Ge-imogolite nanotubes in isomalt with tunable inter-tube distances

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