Polymer, topology and reduced dimensions can have a significant impact on the properties and phase transitions' polymeric films with thicknesses below a few hundred nanometers. We study, the impact of thee effects in the case of thin Earns Of cyclic and linear poly(N-isopropylacrylamide) (PNIPAM) exposed to water Vapor: Specifically, we monitor the selling kinetics of the thin PNIPAM films; their interfacial interactions, and their LCST-type demixing phase transition, using whit light inter-ferometry and X-ray reflectivity. As the film thickness decreases, the,, swelling ratio increases, presumably due to the increasingly dominant effect of polymer/substrate interactions. The time constants Of the swelling process depend on both the film thickness and the PNIPAM topology. Consistent with earlier observations for PNIPAM solutions, in,thin swollen films of comparable,concentration, cyclic PNIPAM exhibits a broader and thus less cooperative demixing transition than the linear PNIPAM counterpart.