Vapor Pressures of Phenethyl Alcohol in the System Water-Phenethyl Alcohol and the Triblock Copolymer EO4.5PO59EO4.5

The phase diagram of water, phenethyl alcohol (PEA) and the triblock copolymer EO4.5PO59EO4.5, (EO == ethylene oxide, PO = propylene oxide), L101, was determined and the vapor pressures of PEA were measured for different phases. The phase diagram was almost identical to the corresponding one with a simple nonionic surfactant, Laureth 4, (~ C12EO4), but the PEA vapor pressure variation with mole fraction was significantly different reflecting the strong molecular interaction between PEA and the polymer. This distinction was mainly due to difference in molecular size; vapor pressure plots against weight fraction gave curves with only moderate variance. The results were used to discuss the variation in the PEA vapor pressure with time after application of a vesicular solution of PEA stabilized either by L101 or Laureth 4. The moderate differences in vapor pressures had a significant influence on the estimated curves of PEA pressure versus time.