Aggregation behavior of hydrophobically modified polyethyleneglycol (C 12 E 25) in aqueous solution

Aggregation behavior of polyethyleneglycolmonododecylether (C 12 E 25) in a queous solution at 25 degreesC was investigated by static and dynamic light scattering and viscoelastic measurements. C 12 E 25 is found to form star- like sphere micelles with aggregation number N-app=26.0 (+/- 1.5) and the h ydrodynamic radius R-h app=3.0 (+/-0.2) nm in dilute aqueous solution. Conc entration dependencies of the storage modulus G' and the loss modulus G" de monstrate that, with increasing concentration, the solution changes drastic ally from a viscous liquid to a viscoelastic gel at about 30 wt% of C 12 E 25. Some high order peaks in the X-Ray diffraction are observed for 40 wt% solution, suggesting that C 12 E 25 gel exhibits long-range order structure with body-centered cubic lattice. It is concluded that star-like micelles of C 12 E 25 in aqueous solution show a set-gel transition at about 30 wt% to form an ordered structure as the concentration increases.