Phase decomposition in polymer blend films cast on substrates patterned with self-assembled monolayers

Thin polymer films with lateral structures are expected to play an importan t role in future applications (e.g. plastic-based electronic devices). Such structures could be formed when blend films are spun-cast onto substrates patterned with self-assembled monolayers (SAM). The spin-coating process re sults in composition variations accompanied by surface undulations. We have studied both phenomena for PVP/dPS and PVP/PBrS blends, composed of poly(v inylpyridine) (PVP) and deuterated (dPS)- or brominated (PBrS)-polystyrene. SAM stripes of HS(CH2)(15)CH3 on Au substrate ('bare' or covered with HS(C H2)(15)COOH) were used as the pattern with periodicity of 4 mum. Transfer o f the pattern from the substrate to the film interior and to the film surfa ce was examined with secondary ion mass spectroscopy (SIMS) and atomic forc e microscopy (AFM) combined with selective dissolution of blend components. Characteristic size D of the phase domains corresponding to given spin-cas ting conditions was determined for the blends cast on homogeneous SAM subst rate. Fourier transform analysis (FTA) of topographic (AFM) and composition al (SIMS) maps was performed. FTA confirms that the pattern-directed compos ition variations coincide with the surface undulations. It reveals also tha t most effective pattern transfer is achieved for the size D commensurate w ith the pattern periodicity for the carefully adjusted polymer-substrate in teractions. (C) 2001 Elsevier Science Ltd. All rights reserved.