Rheological properties of micellar aqueous solution of hydrophobically modified poly(ethylene glycol) (C12E25)

The rheological properties of micellar aqueous solutions of hydrophobically modified ethylene glycal oligomer, poly(ethylene glycol) monododecyl ether (C12E25), have been studied over a wide range of concentraton and temperature. The micellar solution of C12E25 exhibits a sol-gel transition accompanied by disorder-to-order transition of micelle particles. The following conclusions were made (1) The sol solution behaves like an ordinary viscous liquid of Newtonian flow, presenting no sign of any change in associations. (2) Under shear deformation, the gel exhibits a yield point around the strain of a few per cent, followed by a plastic flow with further deformation. The plastic flow exhibits a strong non-Newtonian flow. (3) As the shear rate increases, the sol-gel transition temperature, observed by steady-flow viscosity, becomes lower with a reduced sharpness of transition. (4) The long-range structural order of the lattice in the gel, destroyed by the plastic flow, is suggested to substantially recover in 10-100 s.