Atomistic simulations of confined species in 2D nanosructures: clays and C-S-H gel

Abstract

In this thesis, atomistic simulations have been used to study and predict the properties of molecules and materials. The information provided by the molecular dynamics simulations complements and supports the experiments, helping in the interpretations of the results and serving as a guide for the design of new materials. First, the intercalation of two organic dyes, LDS-722 and pyronin Y, with two smectite clays, Laponite and saponite, has been studied. The simulation of these dye/clay systems has enable the understanding of their photophysical behavior, the dye aggregation and its diffusivity. The mechanical properties of these hybrid materials has also been characterized. Second, the retention of radiocesium in calcium silicate hydrates (C-S-H gel) has been evaluated, considering the impact of Cs concentration, Ca/Si ratio, counterions and Al incorporation in the silicate chains to form C-A-S-H. Third, the strengthening mechanisms in C-S-H gel that incorporates organic additives, APTES and PEG, has also been explored by molecular dynamics simulations. The bulk and Young¿s moduli have been determined by applying a hydrostatic and uniaxial pressures to the simulated systems, considering the effects of the hydrostatic pressure on the silicate chains and hydrogen bond network. The results presented in this thesis contribute to a better understanding of the guest-host interactions at atomic scale in the studied systems and may help in the design of new materials.