Phase Behavior of Poloxamer 188 Aqueous Solutions at Subzero Temperatures: A Neutron and X-ray Scattering Study
Xiaoda Yuan, Susan T. Krueger, Michael Sztucki, Ronald L. Jones, Joseph E. Curtis, Evgenyi Shalaev
Phase transitions of poloxamer P 188 aqueous solutions during cooling and heating are investigated using small angle neutron scattering (SANS) and small- and wide-angle X-ray scattering (SAXS and WAXS). It is shown that P 188 solution (10 % (w/w)) undergoes the following sequence of the phase transitions during cooling from 25 to -150 °C: micelle solution, solution of monomers, two-phase mixture of cubic mesophase + ice, and finally crystalline P 188 + ice. Formation of the cubic phase during freezing is likely to be triggered by water freezing to ice and corresponding freeze-concentration of the remaining solution. Cubic-to-crystalline P 188 transformation is a relatively slow process, which takes place on minutes and hours timescale. During heating of the frozen solutions, the sequence of the phase transitions is reversed: crystalline P 188 + ice, mesophase + ice, monomer solution + ice, monomer solution, and finally micelle solution. Similar phase transitions are detected for dilute solutions of P 188 (1 % (w/w)) except that micelle formation is not observed at 25 °C, consistent with literature reported critical micelle concentration (CMC) at this temperature.
, Krueger, S.
, Sztucki, M.
, Jones, R.
, Curtis, J.
and Shalaev, E.
Phase Behavior of Poloxamer 188 Aqueous Solutions at Subzero Temperatures: A Neutron and X-ray Scattering Study, Journal of Physical Chemistry B
(Accessed July 6, 2022)