Phase decomposition in polymer blend films cast on homogeneous substrates modified by self-assembled monolayers

Thin films, formed by polymer blends spun-cast from a blend/solvent solutio n onto a rigid substrate, are used in many practical applications (e.g. pho toresist layers, dielectric coatings). Film preparation process is often ac companied by phase decomposition (PD) during the rapid evaporation of the s olvent. PD is reflected in undulations formed on an air/film interface. We have studied the topography of surface undulations and the phase domain mor phology in thin him blends of polystyrene (PS) and polyisoprene (PI) using atomic force microscopy combined with selective dissolution of blend compon ents. Gold covered with self-assembled monolayers [HS(CH2)(15)COOH](y)[HS(C H2)(15)CH3](1-y) (SAM(y)) was used as a substrate. For films of PS and PI ( 50% by mass) cast from toluene, the PS-rich domains protrude high above the PI-rich matrix forming concave or convex islands for hydrophobic (SAM(0))- or hydrophilic (SAM(1))-support, respectively. Different substrates (e.g. SAM(0.5) and Si with a native oxide layer), solvents (CCl4 chloroform) and PS mass fractions were used to evaluate the extent of this novel effect. (C ) 2001 Elsevier Science Ltd. All rights reserved.