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1.
Drying dissipative structural patterns formed in the course of drying colloidal crystals of silica spheres (110 nm in diameter)
in water, methyl alcohol, ethyl alcohol, 1-propyl alcohol, diethyl ether, and in the mixtures of ethyl alcohol with the other
solvents above have been studied on a cover glass. The macroscopic broad rings were formed in the outside edges of the dried
film for all the solvents examined. Furthermore, much distinct broad rings appeared in the inner area when the solvents were
ethyl alcohol, methyl alcohol, and their mixtures. Profiles of the thickness of the dried films were sensitive to the organic
solvents and explained well with changes in the surface tensions, boiling points, and viscosities of the solvents. The macroscopic
and microscopic spoke-like crack patterns formed. The drying area (or the drying time) increased (or decreased) as the surface
tension of the solvent decreased. However, the absolute values of these drying parameters are determined also by the boiling
points of the solvents. Importance of the fundamental properties of the solvents is supported in addition to the characteristics
of colloidal particles in the drying dissipative pattern formation. 相似文献
2.
Tsuneo Okubo 《Colloid and polymer science》2006,285(3):331-337
Sedimentation and drying dissipative patterns formed in the course of drying green tea (Ocha) have been studied in tea cup (Ochawan), glass dish, polystyrene dish, and watch glass. The broad-ring patterns are formed within several tens of minutes in suspension state by the convectional flow of water and colloidal particles of green tea (7 μm in mean size and 5 μm in its dispersion from the mean size). Formation of the broad-ring patterns is retarded when a tea cup is covered with a watch glass, which demonstrates the important role of the convectional flow of tea particles and water induced by the evaporation of water at the air-suspension interface under the gravity. The sedimentary particles are suspended above the substrate plate and always move by the convectional flow of water. The broad-ring patterns become sharp just before the solidification occurs. The broad rings are formed even in an inclined glass dish, though the rings are transformed slightly, which demonstrates the strong convectional flow of the particles. The drying broad rings and the microscopic fine structures are formed in the solidification processes on the bases of the convectional and sedimentation patterns in suspension state. 相似文献
3.
Tsuneo Okubo Junichi Okamoto Shinya Takahashi Akira Tsuchida 《Colloid and polymer science》2009,287(8):933-942
Drying dissipative structures of aqueous solution of poly(ethylene glycol) (PEG) of molecular weights ranging from 200 to
3,500,000 were studied on a cover glass, a watch glass, and a glass dish on macroscopic and microscopic scales. Any convectional
and sedimentation patterns did not appear during the course of drying the PEG solutions. Several important findings on the
drying patterns are reported. Firstly, the crystalline structures of the dried film changed from hedrites to spherulites as
the molecular weight and/or concentration of PEG increased. Secondly, lamellae were formed along the ring patterns especially
at high concentrations and high molecular weights. The coupled crystalline patterns of the spherulites and the lamellae were
observed in a watch glass along the ring structures, supporting the important role of the convection by the gravity during
the course of dryness. The coupled patterns were difficult to be formed on a cover glass and a glass dish, except at the outside
edge of the dried film. Thirdly, the size of the broad ring at the outside edge of the dried film especially on a cover glass
and a watch glass increased sharply as the molecular weight increased and also as the polymer concentration increased.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 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.
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
6.
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
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.
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
9.
Tsuneo Okubo Shinya Kanayama Hiroyuki Ogawa Masato Hibino Keisuke Kimura 《Colloid and polymer science》2004,282(3):230-235
Macroscopic and microscopic dissipative structural patterns formed in the course of drying a deionized aqueous solution of cationic polyelectrolyte, poly(allylamine hydrochloride) on a cover glass have been observed. Drying times range from 40 min at 45 °C to 450 min at 5 °C, and are insensitive to the polymer concentration. Pattern area shrinks toward the center at the low polymer concentrations, and increases as the concentration increases. A macroscopic broad ring pattern, where the polymer accumulates densely, forms in many cases. Beautiful fractal patterns are observed at the microscopic scale. The fractal dimension increases from 1.2 to 1.6 as polymer concentration increases from 10-6 monoM to 10-2 monoM. The relative rates between the water flow at the drying front and the convection flow of water accompanying the movement of polymer are important for the macroscopic and microscopic pattern formation. 相似文献
10.
Tsuneo Okubo Tomio Yamada Keisuke Kimura Akira Tsuchida 《Colloid and polymer science》2006,284(4):396-404
Macroscopic and microscopic dissipative structural patterns formed in the course of drying a series of poly (ethylene glycol)
(PEG) having molecular weights ranging from 1,000 to 2×106 in aqueous solution have been studied on a cover glass. The broad ring patterns of the hill accumulated with the polymers
are formed irrespective of the molecular weights of PEG molecules. The single round hills are formed also in the center in
the macroscopic scale, when the molecular weight is large. The characteristic convection flow of the polymers and the interactions
among the polymers and substrate are important for the macroscopic pattern formation. Cross-like fractal patterns are observed,
especially for the diluted solutions in the microscopic scale. These patterns are determined mainly by the electrostatic and
polar interactions between the polymers and/or between the polymer and the substrate in the course of solidification. Interestingly,
these microscopic patterns are reflected based on the shape and size of the PEG polymers. 相似文献
11.
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
12.
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
13.
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
14.
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
15.
Drying dissipative structural patterns of aqueous solutions of biological polyelectrolytes, sodium poly (α, L-glutamate; NaPGA) and poly (-L-lysine hydrobromide; PLL.HBr), were studied on a cover glass. Below the critical polymer concentration, m* (ca. 0.003 and ca. 0.01 monoM for NaPGA and PLL.HBr, respectively), the dried patterns shrank only around the center of
the initial solution area wetted on a cover glass. Above the m* values, on the other hand, the drying pattern extended throughout the initial solution area. The m* values agreed excellently with the critical polymer concentrations, where the surface tensions started to decrease sharply
as the polymer concentrations increased. The broad rings were always observed in the drying patterns of any solutions examined.
The spoke-like cracks appeared at the polymer concentrations above the m* values and only in the area of the broad rings. Microscopic structures such as cross-like, rod-like, and block-like patterns
formed irrespective of polymer concentrations. Especially, the city-road-like microscopic pattern was observed for PLL.HBr
solutions, which strongly supports the formation of crystal structures of PLL.HBr that remain in the whole processes of dryness.
These patterns were correlated deeply with the crystal-like orientation of the biological polyelectrolytes at the air–solution
interfaces. 相似文献
16.
Macroscopic and microscopic dissipative structural patterns are formed in the course of drying an aqueous solution of n-dodecyltrimethylammonium chloride on a cover glass. Broad ring patterns of the hill accumulate with detergent molecules to form around the outside edges of the film solution in the macroscopic scale. The drying time (T) and the pattern area (S) decrease and increase respectively, as the detergent concentration increases. T decreases significantly as the ethanol fraction increases in the aqueous ethanol mixtures, whereas S increases as the fraction increases. Both T and S decrease as the concentrations of KCl, CaCl2 or LaCl3 increase. Cross-, branch-, and arc-like microscopic patterns are observed in the separated block regions. The convection of water and detergents at different rates under gravity and the translational and rotational Brownian movement of the latter are important for macroscopic pattern formation. Microscopic patterns are determined by the translational Brownian diffusion of the detergent molecules and the electrostatic and the hydrophobic interactions between the detergents and/or between the detergent and cell wall in the course of the solidification. 相似文献
17.
Herewith we present the results of our studies on the effect of confinement on the solvation of ethyl alcohol in aqueous solutions using Raman spectroscopy of the O-H stretching band. Based on Gaussian-Lorentzian deconvolution of the O-H band Raman spectra we investigate the local structures created between water-water, water-alcohol, and alcohol-alcohol molecules, which are directly related to the solubility of the liquids. Comparison of the responses in bulk solutions and in solutions confined in the pores of the gelatin gel shows that for high ethanol concentrations solubility significantly increases with decrease of the pore sizes. 相似文献
18.
Macroscopic and microscopic dissipative structural patterns formed in the course of drying the fractionated and monodisperse bentonite particles (plate-like in their shape) in aqueous deionized suspension and in the presence of NaCl have been studied on a cover glass. The patterns coexisted with the broad ring of the hill accumulated with the particles and with the round hills are formed around the outside edges of the film and in the center, respectively, in the macroscopic scale. By the addition of NaCl the pattern shifts from the broad ring to the round hill in the center. The spoke-like cracks, which have been observed for the suspensions of the spherical particles so often hitherto, are not observed at all for the bentonite suspensions. The characteristic convection flow of the particles and the interactions among the particles and substrate are important for the macroscopic pattern formation. Wrinkled, branch-like and/or star-like fractal patterns are observed in the microscopic scale. These patterns are determined mainly by the electrostatic and polar interactions between the particles and/or between the particle and the substrate in the course of drying. 相似文献
19.
Okubo T Shinoda C Kimura K Tsuchida A 《Langmuir : the ACS journal of surfaces and colloids》2005,21(22):9889-9895
Macroscopic and microscopic dissipative structural patterns form in the course of drying a series of aqueous solutions of polyoxyethylenealkyl ethers. The shift from the single round hill with accumulated surfactant molecules to the broad ring patterns of the hill in a macroscopic scale occurs as the HLB (hydrophile-liophile balance) of the surfactant molecules increases. The patterns correlate intimately with the HLB values of the surfactants. Microscopic patterns of small blocks, starlike patterns, and branched strings are formed. The size and shape of the surfactant molecules themselves influence the drying patterns in part. The pattern area and the time to dryness have been discussed as a function of surfactant concentration and HLB of the surfactants. The convection flow of water accompanying the surfactant molecules, the change in the contact angles at the drying frontier between solution and substrate in the course of dryness, and interactions among the surfactants and substrate are important for the macroscopic pattern formation. Microscopic patterns are determined in part by the shape and size of the molecules, translational Brownian movement of the surfactant molecules, and the electrostatic and hydrophobic interactions between surfactants and/or between the surfactant and substrate in the course of solidification. 相似文献
20.
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