In this work, the adhesion energies of two dissimilar polymer films after thermal bonding are studied. The films were formed from the emulsions of polycaprolactone (PCL) and nylon-6 (N6) spin-coated onto metal substrates. After that, the solidified blend polymer films on the metal substrates were faced with additional PCL films on metal substrates and thermally bonded to them. The surface structure of blend films was elucidated prior to thermal bonding by staining them using Rhodamine B. The dye stained only N6 leaving PCL undyed and the exposed structure was analyzed using digital photography, which revealed the surface concentration of PCL, as well as the N6 and PCL distributions over the surfaces. It was discovered that PCL-N6 domains would remain partially mixed, influencing the adhesion energy measured. (C) 2017 Elsevier Ltd. All rights reserved.