Molecular dynamics simulation of the aggregation phenomenon in the late stages of silica materials preparation

Molecular dynamics simulations are employed to investigate the aggregation behavior at the late stages of silica production in a colloidal solution to find new insights into the structures and dynamics of the produced aggregates and pores. The implemented theoretical investigations used the Amorphous cell and Forcite modules, and Dreiding force field of Materials Studio package. The key thermodynamic parameters, mean squared displacements, and radial distribution functions were calculated. Results revealed that aggregation occurred in the late stages due to the negative value of Gibbs free energy. Diameters of the generated aggregates and pores continuously increased while the number of aggregates and pores first increased and then decreased. Furthermore, the volume of pores first rose and then fell as the reaction proceeded. Variations of reactant numbers had the noticeable influence on the pores and aggregates topologies. The number of aggregates and pores had an upward trend while their diameters slightly reduced when more effective molecules were involved in the aggregation process. In addition, the shape of the aggregates examined and found that the predominant shapes of the aggregates were spherical. (C) 2018 Elsevier Ltd. All rights reserved.