Wetting of Substrates with Phase-Separated Binary Polymer Mixtures

We investigate a wetting reversal transition in thin films of two-phase mixtures of poly(ethylene-propylene) (PEP) and its deuterated analog (dPEP) on substrates covered by self-assembled monolayers (SAM) whose surface energy, γSAM, is tuned by varying the SAM composition. As γSAM increases from 21 to 24mJ/m², a transition from a dPEP/PEP/dPEP/SAM to a dPEP/PEP/SAM structure occurs at increasing TC-T, where TC and T are the critical and transition temperatures, respectively. The dependence of T on γSAM is predicted by a simple model from surface and interfacial energies of PEP/dPEP.