ADSORPTION AT THE SOLID-SOLUTION INTERFACE AND MICELLE FORMATION IN WATER OF THE POLY(OXYETHYLENE STYRENE OXYETHYLENE) TRIBLOCK COPOLYMER

ABA-type copolymers composed of polystyrene (PS) as the B block and po lyoxyethylene (POE) as the A block, having weight fractions (n(PS)) of PS and M(n) values in the ranges 16-35% and 12 000-27 000 respectivel y, were synthesized by sequential anionic polymerization. Micelle form ation in water by triblock copolymers in the concentration range 10(-5 )-1 g dm-3 was investigated by fluorescence probing (FP) and small-ang le X-ray scattering (SAXS) methods. The data obtained by the FP method indicate that the CMC is extremely small and not observable over the concentration range studied. The micelle size determined by SAXS was f ound to increase with the total copolymer chain length. The results ar e in good agreement with the Star model, and a power-law dependence is found between the radius of gyration R of the micelles and the M(n) v alues of the copolymers investigated. Adsorption measurements from wat er onto titanium dioxide particles were made with copolymer concentrat ions ranging from 10(-1) to 1 g dm-3. The maximum amount adsorbed and the surface density were found to decrease with increasing n(PS) and m olecular weight of the PS block respectively.