tion may proceed only in a melt state of the system where Experimental results are presented on polymer adsorption inthe molecular mobility of polymer chain is high enough. vestigations of two-phase solutions where simultaneous adsorbent This statement is valid both for blends of linear polymers contact occurs with both the phases. Adsorption measurements and interpenetrating polymer networks, IPNs. However, if were performed from highly concentrated two-phase solutions (C in IPN, the surface segregation proceeds from the very beginΣ· C*) of the incompatible ternary system polystyrene (PS) -polyning in an initially one-phase system, for polymer blends (butyl methacrylate) (PBMA) -CCl 4 . Preferential PS adsorption the conditions are determined by the type of critical solution was observed as compared with PBMA in the whole concentration temperature. Since the majority of linear blends has LCST, range. Addition of fumed silica to highly concentrated polymer the surface segregation of such a systems in melt should blend solutions leads to increasing of PBMA concentration, which is probably caused by the improvement of thermodynamic compat-proceed from the two-phase state. ibility of PS and PBMA in the presence of adsorbent. Using NMR Surface segregation enhances phase separation in the sysspectroscopy, the fraction of immobilized polymer segments was tem. Enrichment and depletion of the surface layer in alloy determined and total adsorption layer thickness was calculated. components should be considered as phase separation in Great values of adsorption and adsorption layer thickness with microvolumes near the interface. small fraction of segments anchored to the surface are caused by The effects of surface segregation take place only for the adsorption of macromolecular aggregates. The results obtained are systems with asymmetric interaction with a solid surface explained by the continuous change of the thermodynamic quality (x AS x x BS ). In the course of the alloy formation, in the of the ''mixed'' solvent, which governs the phase separation presence of a solid, two proceed simultaneously: surface processes in solutions of two incompatible polymers. α§ 1997 Academic Press segregation and phase separation.