A SAXS study of the structure of gels formed by mixtures of polyoxyalkylene triblock copolymers

Small‐angle X‐ray scattering was used to characterise aqueous micellar gels of triblock copolymers E 137 S 18 E 137 , E 82 S 9 E 82 , E 76 S 5 E 76 , E 62 P 39 E 62 , and of two mixtures: E 137 S 18 E 137 and E 62 P 39 E 62 (Mix 1) and E 82 S 9 E 82 and E 62 P 39 E 62 (Mix 2), each 50/50 wt%. E = oxyethylene, CH 2 CH 2 O; S = oxyphenylethylene, OCH 2 CH(C 6 H 5 ); and P = oxypropylene, OCH 2 CH(CH 3 ). Within the concentration and temperature ranges investigated (30–40 wt% copolymer, 20–80 °C), spherical micelles of copolymers E 137 S 18 E 137 , E 82 S 9 E 82 and E 62 P 39 E 62 packed into body‐centred cubic (BCC) structures. Gels of E 76 S 5 E 76 were stable only at high concentrations and low temperatures, and a 70 wt% copolymer solution at T = 30 °C formed a hexagonal gel consistent with cylindrical micelles. It is likely that the mixed copolymers would form two distributions of micelles, and more complex structures were expected. However, gels of Mix 2 had well‐ordered BCC structures, while the less ordered gels of Mix 1 were also best characterised as BCC. Copyright © 2006 Society of Chemical Industry