Thermodynamic Modelling of Small-Molecule Interactions with Amorphous Solids

The process by which small gas phase molecules are taken up by solids is commonly described as gas sorption. Gas sorption, especially of water, flavor and fragrance molecules, into amorphous solids is critical in many personal care products. Recent work has highlighted the complexity of these sorption processes in amorphous solids, highlighting the importance of the small molecule solubility into the amorphous phases present.

The project will use molecular based models to predict small molecule solubility in amorphous solids in order to model the sorption isotherms of small molecules in amorphous solids, using of both equilibrium and non-equilibrium approaches. The challenge is to incorporate in the SAFT approach a way to account for crystalline or amorphous polymers (usually, we take them always to be amorphous).

We will calculate phase diagrams related to the “VLE” (of fluid-vapour”) or solubility boundaries of the gas and the polymers at different conditions and for different polymers/gases. We will compare some of these results with more classic polymer equations based on equilibrium lattice fluid models (e.g., Sanchez–Lacombe), non-equilibrium lattice fluid theory (NEFL) and the molecular-based statistical associating fluid theory (SAFT)1.

The NELF model can describe the solubility of gases and liquids in amorphous polymers whilst the SAFT models have been applied the solubility of CO2 and gases in polymers. The SAFT approach is firmly based on statistical mechanics, starting from the proposition of a molecular-scale model (an intermolecular pair potential), and delivering accurate bulk properties at the macroscale.

Experimental data to inform and validate this modelling project will come from another studentship.

This 4 year project would suit a graduate in chemical engineering, physics or a related discipline with an interest in computational modelling. Work would be undertaken at Imperial College, with two 3 months industrial secondments to P&G. The post will be within the CDT in Theory and Simulation of Materials: http://www.imperial.ac.uk/theory-and-simulation-of-materials
Please email your Curriculum Vitae, to [Email Address Removed]. Informal enquiries are also welcome.