The swelling and cleaning behavior of layers of a non-cross-linked acrylate-styrene copolymer, simulating fouling layers found in emulsion polymerization reactors, in aqueous sodium hydroxide (NaOH), was studied using the novel measurement technique of fluid dynamic gauging. The polymer exhibited swelling, dissolution, and deswelling, depending on temperature and pH in the range 7-13.4. The mechanisms were elucidated using FT-IR spectroscopy and AFM. The swelling profiles exhibited case II diffusion behavior, the rate of swelling being proportional to the change in free volume on swelling. The effect of thickness was also studied using single and double polymer layers; the swelling rate and extent of swelling were independent of the initial thickness only when the films were made of a single layer.