Anisotropic swelling in hydrogels formed by cooperatively aligned megamolecules

Okajima, Maiko K.; Mishima, Ryosuke; Amornwachirabodee, Kittima; Mitsumata, Tetsu; Okeyoshi, Kosuke; Kaneko, Tatsuo

doi:10.1039/c5ra18585h

Cited by 53 publications

(66 citation statements)

References 32 publications

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“…We fabricated LC hydrogels from cast films of sacran cross‐linked by a thermal treatment. The cast films formed a layer structure which was driven by LC domains . During the drying process, nanoplatelets of sacran were formed as a result of self‐assembly .…”

Section: Extraction and Properties Of Cyanobacterial Polysaccharidesmentioning

confidence: 99%

Development of Functional Bionanocomposites Using Cyanobacterial Polysaccharides

Okajima

Sornkamnerd

Kaneko

2018

The Chemical Record

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Cyanobacteria are regarded as very eco-friendly microreactors for the production of various biomolecules such as polysaccharides by fixing not only carbon but also nitrogen in water. Cyanobacterial polysaccharides having various functional groups such as hydroxyls, carboxyls, sulfates, etc. have the ability to interact with metals or inorganics, to create bionanocomposites. Sacran, a supergiant cyanobacterial anionic polysaccharide extracted from the extracellular matrix of Aphanothece sacrum which is mass-cultivated in freshwater, is mainly used to create functional bionanocomposites. Gel-type bionanocomposites of sacran with various metal cations are formed and showed photoresponsive functions. Metal recovery is performed from the sacran bionanocomposite gels. Sacran chains are complexed with multi-wall carbon nanotubes (MWCNT) to give viscose dispersion from which MWCNT bionanocomposites can be collected by electrophoresis. The MWCNT/sacran dispersion retains the capability of adsorbing various metal ions to form hardened hydrogel beads. Finally, natural inorganic sepiolite can be used for sacran bionanocomposites which show an efficient neodymium ion adsorption ability. Thus, cyanobacterial polysaccharides are useful for preparing eco-friendly and functional bionanocomposites with various hard materials.

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Section: Extraction and Properties Of Cyanobacterial Polysaccharidesmentioning

confidence: 99%

Development of Functional Bionanocomposites Using Cyanobacterial Polysaccharides

Okajima

Sornkamnerd

Kaneko

2018

The Chemical Record

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“…Here we choose the cyanobacterial polysaccharide, sacran which forms a giant rod or fiber as the self‐assembled structures with 1 µm diameter and >20 µm length, showing lyotropic liquid crystallinity (LC). By drying the sacran solution from the top‐side‐open cell with a narrow gap, the deposited polymer bridges the substrate walls to form membranes with uniaxial orientation of the rods .…”

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Formation of Polysaccharide Membranes by Splitting of Evaporative Air–LC Interface

Okeyoshi

Joshi

Okajima

et al. 2017

Adv Materials Inter

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loss moduli, G′′ ≈ 2 Pa), [13] the polymer around the air-liquid interface deposits through a drastic increase of the polymer concentration from 0.5 to 100 wt%. This partitioning is a result of vertical membrane formation in a top-side-open cell accompanied by parallel orientation of the micrometer scale, rod-like domains with the three-phase contact line. [10,14] During the drying of polymer solution in the cell, the air-liquid interface is in a similar state as the skin layers of a deswelling gel with buckling patterns. [15,16] The deposited polymer on the air-liquid interface behaves like a lid and the evaporation is restricted. By drying in limited space with a narrow gap, the nonequilibrium state between deposition and hydration near the interface causes accumulation of small depositions at several specific points (pinning). Here, the split meniscus should make the area of the evaporative interface larger. This state continuously achieves both deposition and the evaporation. As a result, the deposited polymer bridges the two parallel substrates and the vertical membrane grows. This is unpredicted heterogeneous condensation of the microrods resulting macrospace partitioning in centimeter scale. However, toward generalization of this simple method to other polymeric materials, the role of interfacial curves and necessary conditions for the membrane formation are still required to be clarified.Here we choose the cyanobacterial polysaccharide, sacran [17][18][19][20] which forms a giant rod or fiber as the self-assembled structures with 1 µm diameter and >20 µm length, [14] showing lyotropic liquid crystallinity (LC). By drying the sacran solution from the top-side-open cell with a narrow gap, the deposited polymer bridges the substrate walls to form membranes with uniaxial orientation of the rods. [20] In order to investigate the reorientation during the drying, we have observed the interfacial atmosphere by polarized light microscopy in detail. In this study, to describe the correlation between the interfacial curve and the partitioning, the geometric effects of the evaporation front are discussed. Ideally, the air-liquid interface shows exponential curves that are mostly determined by the distance from the walls of cells. By controlling the evaporation front three-dimensionally, the necessary conditions for the vertical membrane formation are verified multilaterally.To demonstrate the effect of the interfacial geometry, we use an aqueous sacran solution composed of the self-assembled microrods or microfibers. They stably maintain their shape and Self-assembly methods for colloidal crystals are widely developed by using the evaporative interface and capillary forces. Recently, a distinct phenomenon is discovered of macrospace partitioning by a polysaccharide membrane formed in a limited space by drying its aqueous liquid crystalline solution. Differing from typical fingering patterns, here, the viscous solution is in a nonequilibrium process between the polymer deposition and hydration during drying. By drying...

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“…However, in general, network polymers swell or shrink isotropically, resulting in changes in the size, but not the shape. Therefore, generation of anisotropy in the structure of the network polymers is a prerequisite for the development of unidirectional swelling materials, with only limited examples reported that involved utilization of the liquid crystal (LC) phase, such as liquid crystal (LC) elastomers and gels from the mesophase of LC monomers, and incorporation of organic and inorganic LC mesophases into hybrid polymer gels. Thus, other anisotropic phases, such as crystals, have never been used for the preparation of unidirectional swelling materials.…”

Section: Figurementioning

confidence: 99%

Anisotropically Swelling Gels Attained through Axis‐Dependent Crosslinking of MOF Crystals

2017

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Anisotropically deforming objects have attracted considerable interest for use in molecular machines and artificial muscles.H erein, we focus on an ew approach based on the crystal crosslinking of organic ligands in apillared-layer metal-organic framework (PLMOF). The approach involves the transformation from crosslinked PLMOF to polymer gels through hydrolysis of the coordination bonds between the organic ligands and metal ions,giving anetwork polymer that exhibits anisotropic swelling.T he anisotropic monomer arrangement in the PLMOF underwent axis-dependent crosslinking to yield anisotropically swelling gels.T herefore,t he crystal crosslinking of MOFs should be au seful method for creating actuators with designable deformation properties.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under http://dx.

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Anisotropic swelling in hydrogels formed by cooperatively aligned megamolecules

Abstract: A cyanobacterial polysaccharide, sacran, which has a high molecular length over 30 μm, forms in-plane oriented film by casting. The film creates uniaxially-swelling hydrogels with a micrometer thickness.

Cited by 53 publications

References 32 publications

Development of Functional Bionanocomposites Using Cyanobacterial Polysaccharides

Development of Functional Bionanocomposites Using Cyanobacterial Polysaccharides

Formation of Polysaccharide Membranes by Splitting of Evaporative Air–LC Interface

Anisotropically Swelling Gels Attained through Axis‐Dependent Crosslinking of MOF Crystals

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