SANS from P85/water-d under pressure.

Pluronics are triblock copolymers of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide). Pluronic P85 forms a rich phase behavior when dissolved in water. Unimers are observed at low temperature while micelles form at higher temperatures. Spherical, cylindrical, and lamellar micelles are observed sequentially upon heating. The effect of hydrostatic pressure on the phase boundaries is investigated here using small-angle neutron scattering from a dilute P85 solution in deuterated water. The transition temperatures between these micelle phases are found to rise with increasing pressure. A new phase corresponding to demixed lamellae was observed at high temperature. The effect of pressure was seen to decrease the onset formation line of that new phase.