Depth profiling studies of the surface directed phase decomposition in thin polymer films

External surfaces can significantly alter the phase decomposition (PD) of p olymer mixtures in thin films. The surface mode of PD orders two coexisting phases in organised structures with laminated domain morphology. Such stru ctures are employed in new polymer-based technologies of photoelectronic de vices or microelectronic circuits. We studied the surface mode of PD in thi n films composed of various binary mixtures of polystyrene with its deutera ted- and partially brominated- counterpart. We have examined how PD is infl uenced by: (a) surface active diblock copolymers admired to decomposing ble nds, (b) substrate surface modification, and (c) finite film thickness. Thi n films were studied by nuclear reaction analysis (NRA) and secondary ion m ass spectroscopy (SIMS). The results provided composition profiles as a fun ction of depth in the film with a nanometer precision, comparable with the polymer chain dimensions. Lateral morphology was investigated by means of t he atomic force microscope and optical microscope. Various laminated struct ures composed of 2-, 3-, or 4- layers or column-like structures self-strati fied from initially homogenous films were observed. (C) 1999 Published by E lsevier Science Ltd. All rights reserved.