Solidification of colloidal suspensions

Peppin, S. S. L.; Elliott, Janet A.W.; Worster, M. Grae

doi:10.1017/s0022112006009268

Cited by 167 publications

(200 citation statements)

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“…The (a 0 /d) n term is a correction to the disjoining force on the particle [20]. Peppin et al [27,28] developed mathematical models for the unidirectional solidification of the colloidal suspensions with hard spheres. The investigations were focused on the planar interfaces moving at low velocities (0.1-1 μm/s) by optical observation of the systems, which reach equilibrium by Brownian diffusion [20,27,28].…”

Section: Cryotropic Gelation Features and The Nature Of Freezing Processmentioning

confidence: 99%

“…Peppin et al [27,28] developed mathematical models for the unidirectional solidification of the colloidal suspensions with hard spheres. The investigations were focused on the planar interfaces moving at low velocities (0.1-1 μm/s) by optical observation of the systems, which reach equilibrium by Brownian diffusion [20,27,28]. To understand the critical parameters controlling the stability of solidification interfaces in colloidal suspensions, where the freezing velocities were in the range 10-100 μm/s, X-ray radiography and tomography were used to investigate the stability of a cellular interface [29].…”

Section: Cryotropic Gelation Features and The Nature Of Freezing Processmentioning

confidence: 99%

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Cryogels: Morphological, structural and adsorption characterisation

Gun'ko

Savina

Mikhalovsky

2013

Advances in Colloid and Interface Science

288

205

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*Graphical Abstract (for review)Cryotripic gelation technique allows the synthesis of solid and soft macroporous gels Textural characterisation of cryogel in native superhydrated state with noninvasive methods Adsorption and diffusion characteristics of macroporous cryogels with respect to macromolecules and cells Theoretical modelling of adsorption from aqueous media *Highlights (for review) Please find the revised manuscript entitled "Cryogels: morphological, structural and adsorption characterisation" by Vladimir M. Gun'ko, Irina N. Savina, Sergey V. Mikhalovsky to re-consider for publication in the "Advances in Colloid and Interface Science"The paper was completely edited and changed according to reviewers comments.Sincerely yours, Prof. V. M. Gun'koCover Letter ABSTRACTExperimental results on polymer, protein, and composite cryogels and data treatment methods used for morphological, textural, structural, adsorption and diffusion characterisation of the materials are analysed and compared. Treatment of microscopic images with specific software gives quantitative structural information on both native cryogels and freeze-dried materials that is useful to analyse the drying effects on their structure. A combination of cryoporometry, relaxometry, thermoporometry, small angle X-ray scattering (SAXS), equilibrium and kinetic adsorption of low and high-molecular weight compounds, diffusion breakthrough of macromolecules within macroporous cryogel membranes, studying interactions of cells with cryogels provides a consistent and comprehensive picture of textural, structural and adsorption properties of a variety of cryogels. This analysis allows us to establish certain regularities in the cryogel properties related to narrow (diameter 0.4 < d < 2 nm), middle (2 < d < 50 nm) and broad (50 < d < 100 nm) nanopores, micropores (100 nm < d < 100 m) and macropores (d > 100 m) with boundary sizes within modified life science pore classification. Particular attention is paid to water bound in cryogels in native superhydrated or freeze-dried states. At least, five states of water -free unbound, weakly bound (changes in the Gibbs free energy G < 0.5-0.8 kJ/mol) and strongly bound (G > 0.8 kJ/mol), and weakly associated (chemical shift of the proton resonance  H = 1-2 ppm) and strongly associated ( H = 3-6 ppm) waters can be distinguished in hydrated cryogels using 1 H NMR, DSC, TSDC, TG and other methods. Different software for image treatment or developed to analyse the data obtained with the adsorption, diffusion, SAXS, cryoporometry and thermoporometry methods and based on regularisation algorithms is analysed and used for the quantitative morphological, structural and adsorption characterisation of individual and composite cryogels, including polymers filled with solid nano-or microparticles.

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Section: Cryotropic Gelation Features and The Nature Of Freezing Processmentioning

confidence: 99%

Section: Cryotropic Gelation Features and The Nature Of Freezing Processmentioning

confidence: 99%

Cryogels: Morphological, structural and adsorption characterisation

Gun'ko

Savina

Mikhalovsky

2013

Advances in Colloid and Interface Science

288

205

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“…where D is the particle diffusivity, k is the permeability, η is the fluid viscosity, T is the absolute temperature and P is the mixture pressure (Russel et al 1989;Peppin et al 2006). Given measurements of the permeability and osmotic pressure Π , equation (2.4) can be used to determine the diffusivity as a function of volume fraction.…”

Section: Physico-chemical Properties (A) Freezing-point Depressionmentioning

confidence: 99%

“…For example, in soils composed mainly of silt particles, the ice usually forms nearly planar layers, called ice lenses (Taber 1929;Watanabe & Mizoguchi 2000), whereas in a wide range of clays and colloidal suspensions, the ice can grow in several directions, producing a remarkable variety of patterns (Taber 1929;Chamberlain & Gow 1979;Brown 1984;Deville et al 2007; figure 1). Recently, we proposed a mechanism for ice segregation in freezing colloidal suspensions based on the concept of morphological instability studied in alloys quantitatively applied to the ice-suspension interface (Peppin et al 2006(Peppin et al , 2007(Peppin et al , 2008. The approach relies essentially on treating a colloidal suspension as a 'two-component thermodynamic system' in which the solute particles are vastly larger than the solvent, and by exploiting the physical basis for the dynamics and thermodynamics of pre-melting between these particles and the frozen solvent.…”

Section: Introductionmentioning

confidence: 99%

Morphological instability of a non-equilibrium ice–colloid interface

2009

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We assess the morphological stability of a non-equilibrium ice-colloidal suspension interface, and apply the theory to bentonite clay. An experimentally convenient scaling is employed that takes advantage of the vanishing segregation coefficient at low freezing velocities, and when anisotropic kinetic effects are included, the interface is shown to be unstable to travelling waves. The potential for travelling-wave modes reveals a possible mechanism for the polygonal and spiral ice lenses observed in frozen clays. A weakly nonlinear analysis yields a long-wave evolution equation for the interface shape containing a new parameter related to the highly nonlinear liquidus curve in colloidal systems. We discuss the implications of these results for the frost susceptibility of soils and the fabrication of microtailored porous materials.

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“…If some common characteristics between these two systems are encountered, such as the relationship between the structural wavelength and the interface velocity [7], it is nevertheless necessary to incorporate the specificities associated to particles in the analysis. Such an effort is under way, under the so-called "colloidal alloys" designation [8][9][10][11]. Experimental results gathered so far concentrated on low interface velocities systems (<1 micron/s), which are hardly relevant to the conditions encountered in the materials processing route called freeze-casting.…”

Section: Introductionmentioning

confidence: 99%

In Situ X‐Ray Radiography and Tomography Observations of the Solidification of Aqueous Alumina Particles Suspensions. Part II: Steady State

Deville

Maire

Lasalle

et al. 2009

Journal of the American Ceramic Society

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This paper investigates the behaviour of colloidal suspensions of alumina particles during directional solidification, by in situ high-resolution observations using X-ray radiography and tomography. This second part is focussed on the evolution of ice crystals during steady state growth (in terms of interface velocity) and on the particles redistribution taking place in this regime. In particular, it is shown that diffusion cannot determine the concentration profile and the particles redistribution in this regime of interface velocities (20-40 microns/s); constitutional supercooling arguments cannot be invoked to interpret particles redistribution. Particles are redistributed by a direct interaction with the moving solidification interface. Several parameters controlling the particles redistribution were identified, namely the interface velocity, the particle size, the shape of the ice crystals and the orientation relationships between the crystals and the temperature gradient.

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Solidification of colloidal suspensions

Cited by 167 publications

References 48 publications

Cryogels: Morphological, structural and adsorption characterisation

Cryogels: Morphological, structural and adsorption characterisation

Morphological instability of a non-equilibrium ice–colloid interface

In Situ X‐Ray Radiography and Tomography Observations of the Solidification of Aqueous Alumina Particles Suspensions. Part II: Steady State

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