Thermo-sensitive colloidal crystals of silica spheres in the presence of large spheres with poly (N-isopropyl acrylamide) shells

Okubo, Tsuneo; Mizutani, Taro; Okamoto, Junichi; Kimura, Kouji; Tsuchida, Akira; Tauer, Klaus; Khrenov, Victor; Kawaguchi, Haruma; Tsuji, Sakiko

doi:10.1007/s00396-006-1578-4

Cited by 21 publications

(2 citation statements)

References 37 publications

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“…Colloidal crystals (CCs) assembled from monodisperse hard spheres have attracted substantial interest because of their novel applications in a wide range of disciplines, especially as photonic bandgap materials . Most CCs are assembled from spheres with the same size (unary CC), however, colloidal particles of two sizes can also self‐organize into 2D and 3D binary crystals (binary CCs) . One important advantage of binary CCs over unary ones is their structural diversity, which offers great potential for tuning their properties .…”

Section: Methodsmentioning

confidence: 99%

Facile Assembly of 3D Binary Colloidal Crystals from Soft Microgel Spheres

Liu

Guan

Zhang

2014

Macromol. Rapid Commun.

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It still remains a big challenge to fabricate binary colloidal crystals (binary CCs) from hard colloidal spheres, although a lot of efforts have been made. Here, for the first time, binary CCs are assembled from soft hydrogel spheres, PNIPAM microgels, instead of hard spheres. Different from hard spheres, microgel binary CCs can be facilely fabricated by simply heating binary microgel dispersions to 37 °C and then allowing them to cool back to room temperature. The formation of highly ordered structure is indicated by the appearance of an iridescent color and a sharp Bragg diffraction peak. Compared with hard sphere binary CCs, the assembly of PNIPAM microgel binary CCs is much simpler, faster and with a higher "atom" economy. The easy formation of PNIPAM microgel binary CC is attributed to the thermosensitivity and soft nature of the PNIPAM microgel spheres. In addition, PNIPAM microgel binary CCs can respond to temperature change, and their stop band can be tuned by changing the concentration of the dispersion.

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Section: Methodsmentioning

confidence: 99%

Facile Assembly of 3D Binary Colloidal Crystals from Soft Microgel Spheres

Liu

Guan

Zhang

2014

Macromol. Rapid Commun.

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“…As was described in the "Introduction" section, most researchers including the present authors [63,64] have believed so far that the gel spheres are quite different from the typical colloidal particles, which have interfaces with the medium molecules and are surrounded always with the electrical double layers in aqueous media. However, crystallization of pNIPAm gels in the deionized state with coexistence of the ion-exchange resins took place at the quite low gel concentrations compared with the concentration expected from the excluded volumes of the gel spheres [50][51][52][53].…”

Section: Discussionmentioning

confidence: 90%

Drying dissipative structures of thermo-sensitive gel spheres of poly(N-isopropylacrylamide). Influence of degree of cross-linking of the gels

Okubo¹,

Suzuki

Tsuchida

2012

Colloid Polym Sci

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Drying dissipative patterns of de-ionized suspensions (colloidal crystal state above the critical concentrations of crystallization) of the thermo-sensitive gels of poly (N-isopropylacrylamide) with degrees of cross-linking of and pNIPAm(200-2)) were observed at 20°C and 45°C on a cover glass, a watch glass, and a Petri glass dish. The broad rings were observed, and their size decreased as micro-gel concentration decreased. Formation of the monodispersed agglomerated particles and their ordered arrays were observed. Microscopic drying structures of (a) flickering ordered spoke-lines, (b) ordered rings, (c) net structure, and (d) lattice-like ordered structures of the agglomerated particles are observed. The net and lattice structures formed more favorably at high degrees of cross-linking, at high concentrations of the gels, and/or high temperatures. By the addition of sodium chloride, very large dendrite-like and net structures of the large agglomerated particles formed at 20°C and 45°C, respectively. Importance of the cooperated convectional flow of the agglomerated particles during the drying processes is supported for the ordered array formation. The role of the electrical double layers around the agglomerated particles and the interaction of the particles with the substrate surfaces during dryness are also important for the ordering. The microscopic drying patterns of gel spheres were different from those of linear type polymers and also from typical colloidal spheres, though the macroscopic patterns of gel system such as broad ring formation at the edges of the dried film were similar to other two systems.

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Polymeric Colloidal Crystals

Okubo¹

2014

Encyclopedia of Polymer Science and Technology

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Recent advances in the study on the structural, dynamic and functional properties of polymeric colloidal crystals, mainly in the deionized aqueous suspension, are reviewed. Several important findings are paid attention: (a) Soft‐type colloidal crystallization takes place by the interparticle repulsion originated from the extended electrical double layers. The interaction is opposite to the importance of the interparticle attraction for crystallization of other general crystals, metals, proteins, and ice, for example. (b) Main lattice structures are face‐centered‐cubic ( fcc ) and body‐centered‐cubic ( bcc ) lattices. Packing efficiency, that is, minimizing the free volume is important. (c) Giant‐sized single crystals from the homogeneous and heterogeneous nucleation mechanisms form at the deionized and very diluted aqueous suspensions of monodisperse colloidal spheres. (d) Classical theory of crystallization holds for colloidal crystallization. (e) Viscosity, elasticity, and viscoelasticity of colloidal crystals are reviewed. (f) External field effects (gravitational, electrical, centrifugal forces, and so on) are discussed. (g) Colloidal crystal structure, morphology, and kinetics are quite similar to those of general crystals. (h) The application of colloidal crystals is also reviewed briefly.

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Thermo-sensitive colloidal crystals of silica spheres in the presence of large spheres with poly (N-isopropyl acrylamide) shells

Cited by 21 publications

References 37 publications

Facile Assembly of 3D Binary Colloidal Crystals from Soft Microgel Spheres

Facile Assembly of 3D Binary Colloidal Crystals from Soft Microgel Spheres

Drying dissipative structures of thermo-sensitive gel spheres of poly(N-isopropylacrylamide). Influence of degree of cross-linking of the gels

Polymeric Colloidal Crystals

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