Experimental Simulation of Polymer Mixture Adsorption from Two-Phase Solutions

The simulation of segregation of two polymers near an interface has been realized by studying adsorption from concentrated solutions of incompatible polymers at concentrations above that for coil overlapping and corresponding to one-phase and two-phase states. For solutions that have separated into two phases with increasing component concentration, the adsorption from each phase has been studied separately and the total adsorption from two phases has been calculated. The polystyrene-poly(butyl methacrylate)-CCl4 system was investigated using fumed silica as adsorbent. Simultaneously the fraction of segments of each type immobilized by the surface was determined from NMR spectra. In all cases, poly(butyl methacrylate) is characterized by preferential adsorption. The main features of adsorption are similar in both one-phase and two-phase states; however, the values of adsorption and fraction of immobilized segments are different for adsorption from two separated phases because of the difference in the ratio of components and their concentration in each phase. The total adsorption of poly(butyl methacrylate) from the two-phase state is higher than from the one-phase state. It is concluded that in two-phase systems adsorption proceeds simultaneously from both phases, leading to higher segregation of one of the components.