and, more recently, light scattering, microcalorimetry, fluo-A comprehensive study of sound velocity and apparent specific rescence probing, and gel permeation chromatography techvolume, and adiabatic compressibility and expansibility thermodyniques have provided new insights about the aggregation namic properties of aqueous solutions of a number of POE-POPbehavior of these systems (7-12).
POE triblock copolymers has been carried out in the temperature
Studies of the thermodynamic properties of anesthetic range 10-45ЊC. Three series of the above block copolymers were molecules in aggregates such as micelles have been the focus studied: one having similar relative molar masses but different of some recent work in our laboratory. Triblock copolymers, POP/POE mass ratios (F38, P103, P85); another having the same containing hydrophobic segments of POP and hydrophilic POP/POE mass ratio but different relative molar masses (L64, segments of POE, are being used as model systems to inves-P84, P104 and F38, F68, F108); and a series in which the copolytigate what effect the hydrophobic/hydrophilic balance may mers have the same absolute POP content but different relative have on the location and mechanism of solubilization of molar masses (P103, P104, P108
). An abrupt transition in the temperature dependence of the volumetric and sound velocity inhalation anesthetics in membranes. Relative changes in the properties occurs in the temperature range 10-45ЊC for many of adiabatic compressibility property of a component can be an the copolymers. This is due to the self-aggregation of the copolyeffective measure of changes in this balance as the adiabatic mers. The results of this study show that the relative molar mass, compressibility of hydrophilic and hydrophobic environ-POP/POE mass ratio and POP content of the copolymers are ments differ significantly. The sound velocity is one of the factors that play a role in the self-aggregation of these systems. properties required to obtain the compressibility coefficient The extensive study of the sound velocity property of these systems and in the course of obtaining the adiabatic compressibility extends and confirms the few previous reports that it is a sensitive coefficients of aqueous binary solutions of these polymers, macroscopic probe of the onset of self-aggregation processes in it was evident that the sound velocity property itself is very these systems. The apparent specific volume data of the copolysensitive to the onset of aggregation processes induced by mers has been used to test current models of these aggregates. The increasing temperature and changing composition. There has results show that the POP core contains some water. ᭧ 1997 Academic been no report of a comprehensive study of sound velocity Press or thermodynamic properties of Pluronic systems. As our