Molecular dynamics simulations of surfactants' adsorption in emulsion polymerizations and of CO2 capture by graphene-polymer composites.

Abstract

Adsorption is an increase in the concentration of a dissolved substance at the interface of a solid and a liquid phase due to the operation of surface forces. Adsorption has emerged as an important process for various industrial applications, such as emulsion polymerization and gas separation. Surfactants have a crucial role in emulsion polymerization due to their inward properties; namely, they affect the polymer particles nucleation and prevent them from the coagulation by the reduction of surface tension. However, many aspects of their use are poorly understood and cause significant problems. In this thesis the combination of experimental and computational studies will be reported with the aim to elucidate the adsorption properties of ionic and non-ionic surfactants on hydrophobic polymer surface such as poly(styrene). Also, since the particle nucleation behavior of nonionic surfactants exhibits deviations from the Smith-Ewart model, which described the kinetic mechanism of the particle nucleation typical for ionic surfactant, we seek to take a deeper look of the behavior of these two classes of surfactants at monomer/polymer-water interface during the emulsion polymerization of styrene. Three-dimensional graphene-polymer porous materials have been proposed recently as potential adsorbents for carbon dioxide capture. Owing to their mechanical stability and ease of regeneration they can potentially alleviate short- coming encountered by other sorbents. Molecular dynamics simulation will be performed to study the adsorption of carbon dioxide by different graphene-polymer composite systems. Additionally an estimation of the CO2 selectivity respect to N2 and CH4 will be examined to prove the ability of the composite materials to discriminate against these competing gasses.