CO2‑Expanded alkyl acetates: physicochemical and molecular modeling study and applications in chemical processes

Abstract

Different physicochemical properties of CO2-expanded alkyl acetates (methyl, ethyl, propyl, and isoamyl acetates) have been studied by experimental and molecular modeling methods. Changes in the π* Kamlet−Taft parameter with CO2 pressure were determined by UV−vis spectroscopy by following the hypsochromic shift of Nile Red. Modeling of the systems by molecular dynamics (MD) and equation of state (EoS) methods to assess physical equilibrium, density, and viscosity were performed in order to fully characterize these media with the aim to control the physicochemical properties of these phases by pressure and temperature. The studied expanded phases were used in the fabrication of TiO2 microparticles and the morphological properties measured. It is clear from this study that density, viscosity, and polarity of the expanded phase plays a key role in the morphological properties of the particles obtained. On the basis of these results, we propose these green media and CO2 pressure as a way to control the properties of semiconductor microparticles.