Measuring the solubility of solids in non-solvents: case of polystyrene in alkanes.

We introduce a simple and sensitive technique for measuring extremely low solubilities with a small sample size and small solvent volume. This technique involves measuring the decrease in the thickness of a supported thin film after exposure to a drop of known volume of solvent and removal of the solution. The feasibility of measuring very small changes in film thickness directly translates to the ability to measure extremely low solubility while at the same time using only μL of solvent. We apply the technique to the case of polystyrene with Mw values in the range 2500 g/mol to 22200 g/mol in alkane solvents and show that we can easily measure a solubility of 0.1 g/L using only 1[Formula: see text] g of material and 3[Formula: see text] L of solvent for each sample.