Sol-gel process simulation by cluster-cluster aggregation

Hasmy, Anwar; Jullien, R.

doi:10.1016/0022-3093(95)00079-8

Cited by 77 publications

(73 citation statements)

References 32 publications

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“…In this paper, we show that, allowing cluster deformations during aggregation, the gel time tg does not diverge with the box size, as evidenced in the DLCA model [8,22]. Such an extension also provides a more realistic description of chemical gel formation, since, in experiments (i.e., "polymeric" gels), intraaggregate motions always exist up to some degree, due to free-rotations, bond angle deformations, etc .... We report on a 3d simulation of an aggregation process of f-functional subunits, in which, in addition to rigid motions of clusters, some internal movements are introduced with a tuning flexibility parameter F. This is made possible by extending the efficient Bond Fluctuation method [23,24].…”

Section: Introductionmentioning

confidence: 78%

“…Some hope to reconcile them comes now from Cluster-Cluster Aggregation computer models [5][6][7]. Recently, the modelization of the sol-gel process by the Diffusion-Limited Cluster-Cluster Aggregation (DLCA) [8,9] model shows that several experimental situations can be accounted for. For example, aggregation phenomena of systems like aqueous metal colloids [10], silicon tetramethoxyde [11] and tetraethoxyde [12], alumino-silcates [13], colloidal silica [14], polystyrene [15][16][17] and oil in water emulsions [18].…”

Section: Introductionmentioning

confidence: 97%

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Effect of cluster deformations in the DLCA modeling of the sol-gel process

Jullien¹,

Hasmy

Anglaret³

1997

J Sol-Gel Sci Technol

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Abstract. The diffusion limited cluster-cluster aggregation (DLCA) model is modified by including cluster deformations during aggregation, with a tuning flexibility parameter F. A three-dimensional computer simulation is presented, which starts from a collection of f-functional monomers randomly distributed in a cubic box with a volumic fraction c (concentration) and which uses the highly efficient bond fluctuation algorithm to describe the cluster deformations. It is shown that, for F ~ 0, there exists a well defined threshold value of the volumic fraction below which the realization of all intra-aggregate bonding possibilities prevents the formation of a gelling network. For c > Cg, a true sol-gel transition occurs at a characteristic time tg, after which an infinite cluster (which is self connected via the boundary conditions) appears. In contrast to DLCA, tg does not increase as the box size increases. The transition at Cg is characterized by a divergence of the final clusters size for c < Cg and a divergence of the gel time for c > cg. Several other numerical results are reported.

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Section: Introductionmentioning

confidence: 78%

Section: Introductionmentioning

confidence: 97%

Effect of cluster deformations in the DLCA modeling of the sol-gel process

Jullien¹,

Hasmy

Anglaret³

1997

J Sol-Gel Sci Technol

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“…For the dynamic scaling hypothesis of a decomposing system, which applies to advanced stages (Furukawa, 1985), d is the spatial dimension, d=3, while for colloidal aggregation, the scaling requires d=D f , the fractal dimension of the clusters (Carpineti & Giglio, 1992;Hasmy & Jullien, 1995;Haw, Sievwright, Poon & Pusey, 1995;RamirezSantiago & Gonzalez, 1997). Thus, the universal curve…”

Section: Resultsmentioning

confidence: 99%

“…Aggregation mechanisms have been widely studied both experimentally and theoretically (Hasmy & Jullien, 1995;Haw, Sievwright, Poon & Pusey, 1995;Ramirez-Santiago & Gonzalez, 1997;Van Garderen, Pantos, Dokter, Beelen & Van Santen, 1994) due to the relevance of this phenomenon for a wide range of systems such as aqueous metal colloids (Olivier & Sorensen, 1990), oxide colloidal powders (Dietler, Aubert, Cannell & Wiltzius, 1986;Schaefer, Martin & Keefer, 1985), oil in water emulsions (Bibette, Mason, Gang & Weitz, 1992) or polystyrene particles suspensions (Carpineti & Giglio, 1992;. Two limiting modes of aggregation, endowed with universal character, have been identified and named diffusion-limited cluster aggregation (DLCA) or reactionlimited cluster aggregation (RLCA) according to the probability of primary unit sticking.…”

Section: Introductionmentioning

confidence: 99%

Dynamical scaling property of colloidal aggregation in a zirconia-based precursor sol during gelation

2000

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Zirconia precursor gels, prepared in the zirconium n-propoxide, npropanol, acetylacetone and water system, are studied by small angle X-ray scattering (SAXS). The SAXS intensity pattern exhibits a pronounced maximum for a scattering vector q different from zero. The intensity maximum of the finite q-vector peak increases during gelation while its position q m moves towards smaller and smaller qvectors. The SAXS intensity distribution is well accounted for by recent direct numerical calculations of diffusion-limited cluster aggregation (DLCA). The structural aspects of cluster growth can be described by scaling assumptions. The position q m of the intensity maximum and the structure function S(q/q m ,t) are shown to scale according to S(q/q m ,t) = q m (t) -d F(q/q m ) where F(q/q m ) is a timeindependent scaling function. This scaling requires d=D f , the fractal dimension of the clusters, instead of d=3 for spinodal decomposition. The gel structure is made up of connected fractal clusters, around 50 nm in size, with an apparent fractal dimension of 1.7, resulting from the aggregation of very small primary particles about 2.5 nm in diameter.

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“…Among the models describing the aggregating process, the models based on the simulation of the trajectories of particles, such as Diffusion Limited Cluster-Cluster Aggregation (DLCA) and Reaction Limited Cluster Aggregation (RLCA), can give the best descriptions of the aggregating processes in the real world, and had been verified in many experimental systems [8][9][10][11][12][13][14]. As compared to lattice models of DLCA and RLCA, the offlattice models can give more detailed illustrations on the finer structures of low density porous materials, which will be of great value in studying the properties of low density porous materials.…”

Section: Introductionmentioning

confidence: 99%

Monte Carlo simulation of the diffusion-limited aggregating process of particle suspension systems

Dai

Shan

et al. 2009

Front. Chem. Eng. China

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The aggregating process of particle suspension systems is a very universal phenomena and crucial for various processes both in nature and in industry. In this paper, the aggregating process was simulated with offlattice diffusion-limited cluster-cluster aggregation (DLCA) Monte Carlo programs. The self-similar fractal structures of aggregates have been clearly demonstrated by the statistical analysis of gyration radius distribution and the existence of a scaling distribution of the reduced cluster size. The fractal dimension determined from the relationship between mass and gyration radius of aggregates was 1.80 or so. The fractal dimension of the aggregates drawn from the radial distribution function and structure factor of a single aggregate is about 1.90-2.10. It was also showed that, along with the increasing of particle volume fraction, the fractal dimension will increase in a nearly square root manner, and the spatial range of the fractal structure appearing becomes narrower. Also, the gelation transition can only occur in a particle suspension system where the particle volume fraction is greater than a critical value.

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Sol-gel process simulation by cluster-cluster aggregation

Cited by 77 publications

References 32 publications

Effect of cluster deformations in the DLCA modeling of the sol-gel process

Effect of cluster deformations in the DLCA modeling of the sol-gel process

Dynamical scaling property of colloidal aggregation in a zirconia-based precursor sol during gelation

Monte Carlo simulation of the diffusion-limited aggregating process of particle suspension systems

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