Infrared spectroscopic ellipsometry (IRSE), infrared transmission spectroscopy, and the regularized method of deconvolution are applied cooperatively for the analysis of the process of mixing in thin double layers (about 100 nm each) of poly(n-butyl methacrylate) (PnBMA) and poly(vinyl chloride) (PVC) on gold. For the first time thin polymeric double layers in the nanometer range and the annealing induced interactions have been investigated by IRSE. Spectral changes in the ellipsometric spectra of thin films are compared to those observed in the infrared absorbance of 5-10 mun thick films of the same polymers. The stabilization of conformational states of side-chain ester groups has been revealed after the annealing process and cooling to room temperature. The formation of hydrogen-bond-type interactions between the PnBMA carbonyl and PVC methine groups in the annealed double layer is found. With increasing annealing time the PnBMA/PVC sample progressively approaches a mixed homogeneous state.