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1.
The sedimentation and drying dissipative structural patterns were formed during the course of drying binary mixtures among
colloidal silica spheres of 183 nm, 305 nm, and 1.205 μm in diameter in aqueous suspension on a watch glass, a glass dish,
and a cover glass, respectively. The broad ring-like sedimentation patterns were formed within several hours in suspension
state for all the substrates used. Colorful macroscopic broad ring-like drying patterns were formed for the three substrates.
In a watch glass, macroscopic drying patterns were composed of the outer and inner layers of small and large spheres, respectively.
The two colored layers were ascribed to the Bragg diffractions of light by the dried colloidal crystals of the corresponding
spheres. The width ratio of the layers changed in proportion to the mixing ratio of each spheres. In a glass dish, wave-like
macroscopic drying patterns were observed in the intermediate areas between the outside edges of the broad ring and the inner
wall of the cell. On a cover glass, the sphere mixing ratios were analyzed from the widths of the drying broad rings of the
small spheres at the outside edge. High and distinct broad rings of small spheres and the low and vague broad one formed at
the outer edges and in the inner area, respectively. Drying dissipative pattern was clarified to be one of the novel analysis
techniques of colloidal size in binary colloidal mixtures. 相似文献
2.
Sedimentation and drying dissipative structural patterns formed in the course of drying colloidal silica spheres (305 nm in
diameter) in aqueous suspension have been studied in a glass dish and a watch glass. The broad ring sedimentation patterns
formed within several tenth minutes in suspension state by the convectional flow of water and colloidal spheres. The sedimentary
spheres always moved by the convectional flow of water, and the broad ring patterns became sharp with time. The width of the
broad rings was sensitive to the change in the room temperature and/or humidity. In other words, the patterns became sharp
or vague when the room parameters decreased or increased. Colorful macroscopic drying structures were composed of a broad
ring and the wave-formed patterns. Iridescent colored fine patterns formed in the solidification processes on the bases of
the sedimentation patterns. Beautiful drying patterns were observed for the suspension mixtures of CS300 and NaCl, and were
different from the structures of CS300 or NaCl individuals, which support the synchronous cooperative interactions between
the colloidal spheres and the salt. 相似文献
3.
The drying dissipative patterns of aqueous solutions of simple electrolytes, KCl, NaCl, CaCl2, and LaCl3, were observed on a cover glass. The macroscopic broad rings were formed at the outside edge of the drying film area, which
shrunk from the initial solution area especially at low salt concentrations. The drying area and the broad ring size decreased
as the salt concentration decreased. The microscopic block-like and dendritic cross-like patterns were observed for all the
salts. Size of single crystals dried on a cover glass increased as salt concentration increased. The drying patterns of the
binary mixtures of the salts were also observed. Size of the broad ring increased sharply by mixing. The microscopic patterns
were, on the other hand, insensitive to the mixing. 相似文献
4.
Tsuneo Okubo 《Colloid and polymer science》2007,285(13):1495-1503
The sedimentation and drying dissipative structural patterns formed during the course of drying colloidal silica spheres (CS550,
560 nm in diameter) in an aqueous suspension have been studied in a glass dish and a watch glass. Broad ring patterns were
formed within 20 min in the suspension state by the convectional flow of the colloidal spheres and water. The sedimentary
spheres always moved by the convectional flow of water, and the broad ring patterns became sharp with time. The sharpness
of the broad rings was sensitive to the change in the room temperature and/or humidity. Colorful macroscopic structures were
composed of the broad ring and wave-like patterns, and further colorful and beautiful microscopic fine patterns formed during
the solidification processes based on the convectional and sedimentation structures. The drying patterns of the colloidal
suspensions containing sodium chloride were different from the structures of CS550 or sodium chloride individuals, which support
the synchronous cooperative interactions between the colloidal spheres and the salts. 相似文献
5.
Drying dissipative structural patterns formed in the course of drying ethyl alcohol solutions of rhodamine 6G, uranine, 7-hydroxy
coumarin, and 7-amino-4-(trifluoro methyl)-coumarin are studied on a cover glass. The macroscopic broad ring patterns form
for all the solutions examined, which supported importance of the convectional flow of ethyl alcohol and dye solutes. Dried
area increases as dye concentration increases above the critical dye concentration. Microscopic fine patterns including street-like,
needle-like, and flower-like crystal structures are formed in the solidification processes. Change in the functional side
group moieties of the dyes gives the strong effect on the microscopic drying patterns; even the main chemical structures are
same. Kinetic aspect of the drying patterns is studied. 相似文献
6.
Tsuneo Okubo 《Colloid and polymer science》2008,286(13):1527-1535
In a series of our studies on the dissipative structure formation, this work focused on the sedimentation and drying patterns
of colloidal crystals of poly(methyl methacrylate) colloidal spheres with different sizes (100, 200, 300, and 1,000 nm in
diameter) in a glass dish. During the course of dryness, the brilliant iridescent colors changed. Drying frontier grew from
the central area of the cell toward the outside edge. Macroscopic and microscopic drying patterns of the resulting film from
dried colloidal suspensions showed outer and inner broad rings. Size of the outer rings increased with increasing sphere concentration
but did not altered sphere size, while these factors affected the inner ring size. These observations do not support the pinning
effect proposed by Deegan et al. 相似文献
7.
Tsuneo Okubo 《Colloid and polymer science》2006,285(2):225-231
Convectional, sedimentation, and drying dissipative structural patterns formed in the course of drying ethanol suspensions of colloidal silica spheres (110 nm in diameter) were studied in a glass dish and a watch glass. Vigorous cell convectional flow was observed with the naked eye, and the patterns changed dynamically with time. Broad-ring-like sedimentation patterns were observed in the suspension state just before the suspension was dried up, and the principal macroscopic patterns of the drying patterns were also broad-ring, though the colorful and fine microscopic structures were observed from optical microscopy. 相似文献
8.
Direct observation of the convectional dissipative patterns was successful during the course of dryness of colloidal crystals
of poly (methyl methacrylate) spheres on a cover glass. Formation processes of the convectional patterns of spoke-like lines
were observed as a function of sphere size and also sphere concentration. During dryness of the suspensions, the brilliant
iridescent colors changed beautifully. Macro- and microscopic drying patterns and thickness profiles of the dried film were
observed. Sharp broad rings were observed especially at low sphere concentrations. The water evaporation accompanied with
the convectional flow of water and the colloidal spheres played an important role for these dissipative structure formation. 相似文献
9.
Tsuneo Okubo 《Colloid and polymer science》2006,284(10):1191-1196
Sedimentation and drying dissipative structural patterns formed in the course of drying aqueous suspensions of colloidal silica spheres (1.2 μm in diameter) were observed in the various sizes of watch glasses. The macroscopic broad ring patterns were formed on the inner inclined watch glass in suspension state within a short time after suspension was set. The important role of the convectional flow of water and colloidal spheres for the pattern formation is supported. The influence of sodium chloride was also studied. It was clarified that the sedimentary spheres move toward upper and outer edges along the inclined cell wall by the cell convection and hence the patterns are formed by the balancing between the outside movement and the downward sedimentation of the spheres. Beautiful microscopic drying patterns were also observed from the optical microscopy. 相似文献
10.
Tsuneo Okubo 《Colloid and polymer science》2008,286(12):1411-1423
Convectional, sedimentation, and drying dissipative structural patterns formed during the course of drying aqueous colloidal
crystals of silica spheres (183 nm in diameter) have been studied in a glass dish and a watch glass. Spoke-like convectional
patterns were observed in a watch glass. The broad ring sedimentation patterns formed especially in a glass dish within 30–40 min in suspension state by the convectional flow of
water and colloidal spheres. The macroscopic broad ring drying patterns formed both in a glass dish and a watch glass. The
ratio of the broad ring size in a glass dish against the initial size of suspension, i.e., inner diameter of the glass dish,
d
f/d
i, in this work, were compared with previous work of other silica spheres having sizes of 305 and 560 nm and 1.2 μm in diameter.
The d
f/d
i values in a glass dish increased as sphere concentration increased, but were rather insensitive to colloidal size. The d
f/d
i values on a watch glass also increased as sphere concentration increased, and further increased as sphere size decreased.
Segregation effect by sphere size in a watch glass takes place by the balancing between the upward convectional flow of spheres
in the lower layers of the liquid and the downward sedimentation of spheres. Colorful microscopic drying patterns formed both
in a glass dish and a watch glass. 相似文献
11.
Tsuneo Okubo Daisuke Suzuki Tomoyo Yamagata Akihiro Katsuno Masashi Mizutani Hiroshi Kimura Akira Tsuchida 《Colloid and polymer science》2011,289(7):807-816
Drying dissipative patterns were observed at 25 °C, 33 °C, and 45 °C on a cover glass, a watch glass, and a Petri glass dish
during the course of dryness of colloidal crystals of the thermo-sensitive gels of poly(N-isopropylacrylamide) (PNIPA). Two kinds of broad rings, i.e., transparent ring at the outside edge and the ring in the inner
area from the edge, were observed. Sizes of the former were the same as those of the initial liquids irrespective of gel concentration,
whereas sizes of the latter decreased as gel concentration decreased. These broad rings were composed mainly of the monomeric
and the agglomerated gel particles, respectively. Formation of the monodispersed agglomerated particles and their ordered
arrays in the inner area of the dried film were observed especially on a Petri glass dish and a watch glass. The important
role of the electrical double layers formed around the agglomerated particles is supported for the ordering of the agglomerated
particles. The essential differences in the drying patterns between PNIPA gel spheres and the typical colloidal particles
did not appear. 相似文献
12.
Drying dissipative patterns of de-ionized suspensions (colloidal crystal-state at high concentrations) of the thermosensitive gels of poly (N-isopropylacrylamide) with various sizes (ca. 400–1,500?nm in diameter at 20?°C) were observed at 20 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 gel concentration decreased. Formation of the monodispersed agglomerated particles and their ordered arrays were observed irrespective of gel size. The macroscopic flickering spoke-like patterns were observed for the gel spheres from 70 to 600?nm in diameter at 20?°C, but almost disappeared for extremely large spheres, poly(N-isopropylacrylamide)(1500-5). This work clarified the formation of the drying microscopic structures of (a) ordered rings, (b) flickering ordered spoke lines, (c) net structure, and (d) lattice-like ordered structures of the agglomerated particles. The ordered rings became rather vague as gel size increased. The large net structures formed so often for large gels. Size effect on the lattice patterns was not recognized so clearly. The role of the electrical double layers around the agglomerated particles and the interaction of the particles with the substrate surfaces during dryness are important for the ordering. The microscopic drying patterns of gel spheres were quite different from those of linear type polymers and also from typical colloidal hard spheres, though the macroscopic patterns such as broad ring formation at the edges of the dried film were similar to each other. 相似文献
13.
Influences of temperature and humidity on the drying dissipative patterns of colloidal crystals of silica spheres (103 nm in diameter) were studied. The broad ring pattern, which is one of the typical macroscopic drying structures, became sharp as temperature rose and/or humidity decreased. Furthermore, number of the spoke-like cracks decreased as temperature and/or humidity increased. The water evaporation from a liquid surface to air and the convectional flow of water and colloidal spheres were important for the macroscopic pattern formation. 相似文献
14.
Drying dissipative structural patterns of the colloidal crystals of silica spheres were studied under an dc-electric field. Platinum plate electrodes of anode and cathode were set on a cover glass. The broad hills accumulated with the spheres were observed at the outer edges of the dried film without and also with the electric fields. The column-like structures were formed by the electric flux, and movement of the spheres took place toward anode. The dried film kept colloidal crystal structure, where the nearest-neighbored spheres contact each other more compactly in the areas closer to the anode. Drying times needed for the complete dryness of the suspensions decreased as the strength of the electric field increased. Addition of sodium chloride to the suspensions retarded the movement of spheres toward the anode substantially. 相似文献
15.
Macroscopic and microscopic dissipative structural patterns are formed in the course of drying a suspension of Chinese black ink on a cover glass and in a dish. The time for the drying and the pattern area increased as the particle concentration increased. The broad ring patterns of the hills accumulated with the particles formed around the outside edges on a macroscopic scale. The height and the width of the broad ring increased as the particle concentration increased. The spokelike patterns of the rims accumulated with particles were also formed on a macroscopic scale. Microscopic patterns of colloidal accumulation were observed over the whole region of the pattern area. Various types of convection cells were observed on a cover glass and in a dish at 25–80 °C. A time-resolved observation of the drying process was also made. The convections of water and the colloidal particles at different rates under gravity and the translational and rotational Brownian movement of the particles were important for the macroscopic pattern formation. Microscopic patterns were determined by the translational Brownian diffusion of the particles and the electrostatic and the hydrophobic interactions between the particles and/or between the particles and the cell wall in the course of the solidification of the particles. 相似文献
16.
Tsuneo Okubo 《Colloid and polymer science》2008,286(11):1307-1315
Direct observation of the convectional dissipative patterns at room temperature was successful on a cover glass during the
course of dryness of colloidal crystals of poly(methyl methacrylate) colloidal spheres. Formation processes of the convectional
patterns of spoke-like lines were observed as a function of sphere size and also sphere concentration. During dryness of the
suspensions, the brilliant iridescent colors changed beautifully. Macroscopic and microscopic drying patterns of the dried
film were observed. Multiple broad ring-like patterns were observed especially at low sphere concentrations. The water evaporation
accompanied with the convectional flow of water and the colloidal spheres played an important role for the dissipative structure
formation. 相似文献
17.
Tsuneo Okubo 《Colloid and polymer science》2006,284(12):1395-1401
Sedimentation and drying dissipative structural patterns formed in the course of drying colloidal silica spheres (1.2 μm in diameter) in aqueous suspension have been studied in a glass dish and a polystyrene dish. The broad ring patterns are formed within a short time in suspension state by the convection flow of water and colloidal spheres. The broad ring patterns are not formed when a dish is covered with a cap, which demonstrates the important role of the convectional flow of silica spheres and water accompanied with the evaporation of water on the air-suspension interface. The sedimentary spheres always move by the convectional flow of water, and the broad ring patterns became sharp with time. Broad ring and microscopic fine structures are formed in the solidification processes on the bases of the convectional and sedimentation patterns. Drying patterns of the colloidal suspensions containing sodium chloride are star-like ones, which strongly supports the synchronous cooperative interactions between the salt and colloidal spheres. 相似文献
18.
Macroscopic and microscopic dissipative structural patterns formed in the course of drying a series of the colloidal silica spheres ranging from 29 nm to 1 m in diameter have been observed in the aqueous deionized suspension on a cover glass. The broad ring patterns of the hill accumulated with the silica spheres are formed around the outside edges in the macroscopic scale for all spheres examined. The spoke-like cracks are also observed in the macroscopic scale and their number decreases sharply as sphere size increases. The pattern area and the time for the dryness have been discussed as a function of sphere size and concentration. The convection flow of water accompanied with that of the silica spheres and interactions among the silica spheres and substrate are important for the macroscopic pattern formation. The microscopic fractal structures of the wave-like patterns and branched strings are formed. Their fractal dimensions are determined. Microscopic patterns form in the narrow range of sphere sizes and concentrations and are determined mainly by the electrostatic and polar interactions between the spheres and/or between the sphere and substrate in the course of solidification. 相似文献
19.
Macroscopic and microscopic dissipative structural patterns formed in the course of drying the deionized aqueous colloidal
crystal suspensions of silica spheres (diameter: 103 nm) on a cover glass have been observed. Spoke-like and ring-like patterns
are formed in the macroscopic scale; the former is the crack in the sphere film and the latter is the hill accumulated with
spheres formed around the outside edge. The neighbored inter-spoke angle, thickness of the film, and other morphological parameters
have been discussed as a function of sphere concentration, concentration of sodium chloride, and the inclined angle of the
cover glass. Fractal patterns of the mud cracks are observed in the microscopic scale. Capillary forces between spheres at
the air-liquid surface and the relative rates between the water flow at the drying front and the convection flow of spheres
are important for the pattern formation.
Electronic Publication 相似文献
20.
Drying dissipative patterns of deionized suspensions (colloidal crystal state at high concentrations) of the thermo-sensitive
gels of poly(N-isopropylacrylamide) with low degree of cross-linking of 0.5% (318 nm and 116 nm in the hydrodynamic diameter at 25 °C and
45 °C) 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. This work clarified the formation of the drying microscopic structures of (a) flickering ordered spoke-lines, (b) ordered rings, (c) net structure, and finally (d) lattice-like ordered structures of the agglomerated particles. The net and lattice structures formed more favorably at higher temperatures
and/or higher degree of cross-linking of the gels. Importance of the 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 quite different from those of linear-type polymers and also from typical
colloidal spheres, though the macroscopic patterns such as broad ring formation at the edges of the dried film were similar
to each other. 相似文献