PRESSURE-INDUCED MELTING OF MICELLAR CRYSTAL

Aqueous solutions of triblock copolymers of poly(ethylene oxide) and p oly(propylene oxide) aggregate at elevated temperatures into micelles which for polymer concentrations greater-than-or-equal-to 20% make a h ard sphere crystallization to a cubic micellar crystal. Structural stu dies show that pressure improves the solvent quality of water, thus re sulting in decomposition of the micelles and consequent melting of the micellar crystal. The combined pressure and temperature dependence re veals that in spite of the apparent increase of order on the 100 angst rom length scale upon increasing temperature (decreasing pressure) the overall entropy increases through the inverted micellar crystallizati on characteristic.