Phase behaviour of THF-water mixtures in nanoscale confinement

Understanding the properties of fluids confined to nanometer scale pores is essential to predict and control a wide range of natural and industrial processes. In this proposal we would like to study the phase behaviour of mixtures of tetrahydrofuran (C4H8O, THF) and water in mesoporous silicas with pores of the order 3 - 10nm diameter. At the compositions we would like to study (1:3.3 and 1:17 THF:water) the liquids are miscible at ambient temperature, but sit under a critical point for closed-loop phase separation. By measuring the contrast matching points of liquids to the silica using two different methods (A - individual components matched, B overall mixture only matched) we will be able to confirm and quantify the nature of surface phase separation. We will study two mesoporous silicas: MCM-41 (~3 nm pores) and SBA-15 (~10nm pores). Our hypothesis based on our previous experiment on NIMROD (RB2210033) is that we will see demixing - we are excited to confirm and quantify this effect. We note also that THF-water is a clathrate forming system, and parallel studies are unearthing fascinating confinement effects at lower temperatures.