Modelling and simulation of sol-gel nanocomposites is a promising method for understanding the properties at molecular level and consequently improve and quicken the design of such materials. In the present chapter, a hierarchical procedure for bridging the gap between atomistic and macroscopic modeling via mesoscopic simulations will be presented and discussed. Multiscale molecular modelling is first introduced as a general concept and then applied to sol-gel nanocomposites. The procedure is applied to a model system, chosen as typical of sol-gel nanocomposites, namely the 3-glycidyloxypropyltrimethoxysilane (GPTMS) network with ZnS nanoparticles dispersed in the organic matrix. Details of each scale simulation protocols as well as the scales integration are given in this chapter. Finally, it is shown how macroscopic properties of the sol-gel nanocomposite of interest are estimated using the multiscale molecular simulation protocol described. Calculated values at different scales, but particularly at macroscale are compared with experimental data to show the reliability of the proposed approach.
