Gel structure and crystal nucleation

Halberstadt, E. S.; Henisch, H.K.; Nickl, J.J.; White, E. W.

doi:10.1016/0021-9797(69)90129-5

Cited by 42 publications

(22 citation statements)

References 2 publications

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“…The pH during gelling has a profound influence on gel structure. As pH increases the gel structure changes from a distinctly box-like network to a structure consisting of loosely bound platelets which appear to lack cross linkages; the cellular nature becomes less distinct [11]. Thus, the observed decrease in xZ/t and D.~ are in conformity with the above mentioned facts within the limits of experimental accuracy.…”

Section: Ph Variation Of Gel Mediumsupporting

confidence: 89%

Estimation of diffusion coefficient of Ba++ ions in silica gel from periodic precipitation of BaMoO4

Kurien

Vaidyan

Ittyachen

1982

Colloid & Polymer Sci

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Formation of Liesegang rings on the growth of BaMoO4 crystals in silica gel by single diffusion is discussed. The rhythmic precipitation is found to be influenced profoundly by (a) the molarity of inner and outerelectrolytes (b) the age of gel and (c) the pH of the gel medium. The 'time law', 'spacing law' and the law relating diffusion depth and width are verified. A method to estimate the diffusion coefficient of the outer electrolyte in the gel medium is developed and calculated for Ba++ions.

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Section: Ph Variation Of Gel Mediumsupporting

confidence: 89%

Estimation of diffusion coefficient of Ba++ ions in silica gel from periodic precipitation of BaMoO4

Kurien

Vaidyan

Ittyachen

1982

Colloid & Polymer Sci

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“…X-ray analysis revealed random orientation present in the freezedried clay, therefore, they concluded, that in quick freezing ice formed in the vitreous state rather than as crystals, thereby preventing change in the fabric. Halberstadt et al (1969) studied samples of silica and gelatin gels prepared by a liquid nitrogen freeze-dried technique and concluded "the gels were not damaged by this procedure and the silica structure remained essentially intact". GiUott (1969) has suggested, however, ice crystals have more chance to form if moist samples are immersed directly in liquid nitrogen.…”

Section: Methodsmentioning

confidence: 99%

Fabric of Kaolinite and Illite Floccules

O’Brien

1971

Clays and clay miner.

122

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Abstraet-A scanning and high voltage electron microscope study of the fabric of laboratory sedimented moist uncompressed kaolinite and illite floccules reveals an abundance of face-face flake orientation in the porous clay network. Clays were flocculated in the laboratory in both distilled water and slightly saline (1 g/l. NaCI) water using various clay concentrations. Floccules taken from the moist clay mass were prepared for study by freeze-drying and impregnation with polyethylene glycol.There is little difference in the fabric of kaolinite flocculated in distilled or slightly saline water. The fabric is dominated by a 3-dimensional network of twisted chains of face-face oriented flakes having the appearance of a stair-stepped cardhouse. Illite floccules in distilled water also consist of abundant face-face oriented overlapping flakes. However, in salt water there is a more even mixture of fabrics-edge-to-face flooculation of individual platelets and also stepped clusters of face-to-face oriented flakes, the latter being more abundant.It is suggested that under the experimental conditions the double layer of each clay panicle is compressed resulting in an increase in the importance of van der Waals forces of attraction. As a result flakes approach each other and rotate into a parallel or subparallel position. The resultant dominant fabric is that of a stepped cluster of overlapping flakes.

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“…As discussed below, this difference often results in structural changes to the gel network. Finally, gels are not equilibrium structures and most likely there is structural evolution that occurs over timescales similar to those used for crystallization experiments 72, 73. While entire books and reviews have been written about gels and gelators,64, 74–78 here we highlight the chemistry and structure of several gels that are commonly used to study biomineralization.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, gelatin can be chemically crosslinked through carboxylic acid groups, to increase thermal stability and change the mechanical properties of the gel 76, 96. Gelatin forms cellular networks, with cavities on the order of tens of micrometers, which are defined by non‐porous walls 72…”

Section: Introductionmentioning

confidence: 99%

“…Through these processes, the network structure in silica hydrogels is established predominantly through covalent interactions2, 64 to form a basic hydrogel composed of cellular networks with porous walls (Figure 1g). The thickness and porosity of the cell walls depends on the concentration (density) of silicate species used in the gel 72. The gelation time varies with silicate reactant concentration,101 pH,102 temperature,103 and the identity of the acid catalyst104 and affects the final structure of the hydrogel network.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Crystal Growth of Calcium Carbonate in Hydrogels as a Model of Biomineralization

Asenath‐Smith

Keene

et al. 2012

Adv Funct Materials

201

307

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A gel is defi ned as a two-component (solid and liquid), continuous, solid-like material with viscoelastic rheological Crystal Growth of Calcium Carbonate in Hydrogels as a Model of BiomineralizationIn recent years, the prevalence of hydrogel-like organic matrices in biomineralization has gained attention as a route to synthesizing a diverse range of crystalline structures. Here, examples of hydrogels in biological, as well as synthetic, bio-inspired systems are discussed. Particular attention is given to understanding the physical versus chemical effects of a broad range of hydrogel matrices and their role in directing polymorph selectivity and morphological control in the calcium carbonate system. Finally, recent data regarding hydrogel-matrix incorporation into the growing crystals is discussed and a mechanism for the formation of these single-crystal composite materials is presented. Future and is researching crystal growth in gels as a means to form nanocomposites.chains form helices (double or single helices) that subsequently aggregate into three-dimensional (3D) bundles, forming a porous network with fi brous characteristics (Figure 1 a,b). [ 82 , 83 ] Both the gelling and melting temperatures can be tailored by chemical modifi cation such as partial hydroxyethylation. [ 84 ] The mechanical behavior of agarose gels is sensitive to molecular weight and concentration [ 85 ] as well as chemical modifi cation.

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Gel structure and crystal nucleation

Cited by 42 publications

References 2 publications

Estimation of diffusion coefficient of Ba++ ions in silica gel from periodic precipitation of BaMoO4

Estimation of diffusion coefficient of Ba++ ions in silica gel from periodic precipitation of BaMoO4

Fabric of Kaolinite and Illite Floccules

Crystal Growth of Calcium Carbonate in Hydrogels as a Model of Biomineralization

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