Effects of guest poly(ethyleneglycol) on the order-to-disorder transition of hydrophobically modified poly(ethyleneglycol) (C12E25) micellar solution

Order-to-disorder transition of micellar aqueous solution of hydrophobically modified ethyleneglycol oligomer, poly(ethyleneglycol) monododecylether (C12E25) with addition of poly(ethyleneglycol) (PEG) has been investigated by means of linear-viscoelastic measurements, X-ray scattering, and differential scanning calorimetry. We have revealed the followings. Added PEG having a chain length similar to that of micellar corona PEG can be incorporated into the micellar lattice of C12E25 aqueous solution with maintaining the body-centered-cubic lattice structure. The transition mechanically observed as the sol–gel transition is a thermodynamical first-order transition of disorder-to-order. The transition temperature decreases with increasing concentration of guest PEG. The stability of micellar lattice is discussed in terms of guest chain localization in the lattice.