Institute for Colloidal Organization

Uji, Japan

Institute for Colloidal Organization

Uji, Japan

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Okubo T.,Institute for Colloidal Organization | Takahashi S.,Gifu University | Tsuchida A.,Institute for Colloidal Organization | Tsuchida A.,Gifu University
Colloids and Surfaces B: Biointerfaces | Year: 2011

Dissipative patterns during the course of dryness of aqueous solution of potassium salt of poly(riboadenylic acid) (KPolyA) in the presence of potassium chloride were studied on a cover glass, a watch glass and a glass dish. Accumulation of KPolyA polymers forming the broad ring area and the drastic change in size and shape of the polymer single crystals depending on the location of the dried film, which are the typical effects of the dissipative crystallization, took place. Polymer crystals formed were spherulites, dendritic and rod-like assemblies, which are composed of the single or double helical chains depending on the pH-value of the initial solution. © 2011.


Okubo T.,Institute for Colloidal Organization | Tsuchida A.,Gifu University
Colloid and Polymer Science | Year: 2014

Macroscopic and microscopic patterns during the course of dryness of aqueous solution in sodium salts of hyaluronic acid (NaHLA) were observed on a cover glass, a watch glass, and a Petri glass dish. Dendritic and rod-like microscopic patterns, which are similar to those of sodium salts of carboxymethyl cellulose, were observed for NaHLA especially on a cover glass and a watch glass. The microscopic patterns of NaHLA are supported to be originated from the hexose groups of polysaccharides, though the similar dendritic patterns are also observed for some of polynucleotides, sodium salts of deoxyribonucleic acid, and potassium salts of poly (riboadenylic acid), for example. Macroscopic broad ring size decreased substantially from the initial size of liquid and decreased slightly as polymer concentration decreased. These observations are consistent with existence of the rather strong interpolymer affinitive forces during the course of dryness. In the coexistence of sodium chloride, microscopic dendritic patterns grew large especially on a cover glass and a watch glass, which was so often observed for polysaccharides examined hitherto. Drying patterns are clarified to be formed by the successive and cooperative processes of evaporation, convection, sedimentation, and solidification. © 2013 Springer-Verlag.


Okubo T.,Institute for Colloidal Organization | Okubo T.,Yamagata University
Macromolecular Symposia | Year: 2010

Convectional, sedimentation and drying dissipative patterns during the course of dryness of suspensions and solutions are reviewed. The whole processes of convection were analyzed in the seven steps: irregular circulation accompanied with the upward heat transportation, global convectional flow from the central area toward outside edge at the surface layers of liquid, cooperative formation of distorted Benard cells, reversal of global flow of convection, growing of the spoke lines from the outside edge toward central area at the liquid surface layers, cluster and further bundle formation of the spoke lines, and the convectional flow by the pinning effect. The sedimentary colloidal particles were suspended above the substrate by the electric double layers and moved by the balancing of the external force fields including convectional flow and sedimentation. Principal macroscopic drying patterns are broad rings and spoke lines. Microscopic patterns such as star, needle, street road, string and cross-like are formed. The stratified structures form from micro to macro scales. Information on the size, shape, conformation and/or flexibility of particles or polymers is transferred cooperatively, and further accompanied with the amplification and selection processes during the course of dryness. Copyright © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Okubo T.,Institute for Colloidal Organization
Colloid and Polymer Science | Year: 2014

Drying patterns of aqueous solutions of potassium salts of poly(riboguanylic acid) (KPolyG), poly(ribocytidylic acid) (KPolyC), and their mixtures KPolyG + KPolyC were studied on a cover glass, a watch glass, and a glass dish at room temperature. Accumulation of the polymers forming the broad rings near the outside edge and also in the inner area of the dried film was observed. The fine multiple ring structures formed, which supports the fact that the affinity of the polymer with the substrate is strong. Typical microscopic drying patterns of KPolyG, KPolyC, and KPolyG + KPolyC were spherulites, dendritic long rods, and sword (harberd)-like rods, respectively. The patterns changed depending on the location in the dried film. The dendritic long rods and sword-like rods were assigned to the crystals of double-stranded and/or triple-stranded helices of the G:C and 2G:C complexes. Cross-like drying patterns that originated from the salt-polymer interaction are also observed. The relationship between the polymer complexation of KPolyG + KPolyC systems and the drying patterns is similar to that of KPolyA (potassium salt of poly(adenylic acid)) + KPolyU (potassium salt of poly(uridylic acid)). © 2014 Springer-Verlag.


Okubo T.,Institute for Colloidal Organization
Colloid and Polymer Science | Year: 2011

Drying dissipative patterns were observed at room temperature on a cover glass, a watch glass, and a Petri glass dish during the course of dryness of aqueous solution of sodium salts of carboxymethyl cellulose (NaCMC) having different molecular weights in the presence of sodium chloride and in their absence. Without salt, the polymers were slightly hygroscopic and did not dry up completely on the substrates. Single crystals of the NaCMC without salt were short rodlike and quite similar to those of the other polysaccharides studied hitherto, i.e., hydroxypropyl cellulose and sodium dextran sulfate. Morphology of the polymer crystals were short rods, long dendritic rods, and/or hedrite assemblies depending on location in the dried film and in the presence of sodium chloride. Spoke-like orientation of the long dendritic rods appeared on a cover glass and a watch glass especially for NaCMC of low molecular weights. © Springer-Verlag 2011.


Okubo T.,Institute for Colloidal Organization
Colloid and Polymer Science | Year: 2013

Macroscopic and microscopic drying patterns were observed on a cover glass, a watch glass, and a Petri glass dish during the course of dryness of aqueous solutions of α-cyclodextrin (αCD), β-cyclodextrin (βCD), and γ-cyclodextrin (γCD), i.e., cone shape oligomers of polysaccharide. For all CD molecules, two kinds of macroscopic patterns, outside and inner broad rings and spoke lines formed. Multi-broad rings were formed for βCD in the inner region of the main broad ring at the outside edge especially at the high concentrations. Cooperative drying processes of the convection, sedimentation, and solidification were clarified. Microscopic drying patterns showing the formation of rod-like and/or sward-like crystals were observed mainly in the direction along the spoke lines. The microscopic patterns of βCD were similar to those of some of polysaccharides and polynucleotides the authors studied previously. α- and γ-cyclodextrins were slightly hygroscopic, and clear-cut drying patterns were not observed. © 2013 Springer-Verlag Berlin Heidelberg.


Okubo T.,Institute for Colloidal Organization
Colloid and Polymer Science | Year: 2013

Macroscopic and microscopic drying patterns were observed on a cover glass, a watch glass, and a Petri glass dish during the course of dryness of aqueous suspensions of similar sized aggregates of diamonds (CD1), which formed from the deionization of the pre-particles of diamond 4 nm in diameter. Two kinds of macroscopic patterns, i.e., outer and inner broad rings, and spoke lines were formed. Cooperative drying processes of the convection, sedimentation, and solidification were clarified. Microscopic drying patterns showing the formation of very large dendritic aggregates from the CD1 particles were observed only when the excess amount of sodium chloride higher than 2 mM coexisted in the initial suspensions before dryness and further initial CD1 concentration is lower than 0.17 wt%. © 2013 Springer-Verlag Berlin Heidelberg.


Okubo T.,Institute for Colloidal Organization
Colloid and Polymer Science | Year: 2013

Distorted colloidal crystal suspension of similar-sized aggregates of diamonds (1.5 μm in diameter) was obtained by the deionization of aqueous suspension of the pre-particles of diamond, 4 nm in diameter. The stability, characteristics, and the rigidity of the crystal-like suspensions were studied. The main cause for the formation of the similar-sized aggregates is deduced to be the cooperation between the van de Waals inter-particle attraction and the repulsion induced by the vigorous thermal motion of the pre-particles. The rigidity was evaluated from the microscopic observation in the sedimentation equilibrium. Fluctuation parameters of the distorted colloidal crystals estimated from the rigidities were between 0.03 and 0.06, which are quite similar to those of typical colloidal crystals and solids of hard spheres. © 2013 Springer-Verlag Berlin Heidelberg.


Okubo T.,Institute for Colloidal Organization
Colloids and Surfaces B: Biointerfaces | Year: 2011

Dissipative drying patterns of aqueous mixtures of potassium salts of poly(riboadenylic acid) (KPolyA) and poly(ribouridylic acid) (KPolyU) were studied on a cover glass, a watch glass and a glass dish at room temperature. Accumulation of the polymers forming the broad rings near the outside edge and the inner area of the dried film was observed. The fine multiple ring structures formed when the affinity of the polymer with the substrate is strong. Microscopic drying patterns changed drastically depending on the location in the dried film. Microscopic drying patterns were mainly dendritic long rods and sword (halberd)-like rods. They are assigned to the crystals of double-stranded and triple-stranded helices of the A:U and A:2U complexes, respectively. Cross-like drying patterns are also observed originated from the salt-polymer interaction. © 2011 Elsevier B.V.


Okubo T.,Institute for Colloidal Organization
Colloid and Polymer Science | Year: 2016

Wetting to drying patterns during the course of drying a water droplet on a printed paper sheet were observed. Blue colored papers with different color densities were prepared with the use of the hydrophilic blue ink and an ink-jet printer on the two kinds of paper sheets for document and pictures. The notched broad ring-like wetting patterns developed fast initially after setting and reached a saturated size of the drying patterns. Size of the broad ring was discussed as a function of time elapsed. A liquid drop remained at the central area for a certain intermediate period and vanished. Hydrophilic blue ink on the paper sheet enhanced the wetting rate significantly. Affinity of a water droplet with the solutes of blue ink on the paper substrate plays an important role on the wetting process in addition to that with the substrate itself. The cooperative drying processes from wetting to solidification took place. © 2015, Springer-Verlag Berlin Heidelberg.

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