AGGREGATION AND CRITICAL-BEHAVIOR OF 2-BUTOXYETHANOL IN WATER

The critical behavior of 2-butoxyethanol (BE) in water was investigated through dynamic and Rayleigh light-scattering measurements. The critical exponents related to the osmotic compressibility and the correlation length are consistent with the Ising predictions, and they apply over a wide range of temperature. At higher values of momentum transfer (Q), the small-angle neutron scattering (SANS) spectra had to be analyzed with a model that accounts for the critical concentration fluctuations and the presence of aggregates of BE having a radius of about 9 A. The correlation length and the critical intensity at zero momentum transfer obtained by light and neutron scattering are in excellent agreement. The freezing point depression of water in the presence of BE was correlated to the self-association of six BE molecules. Our results are discussed in terms of dry and wet aggregates coupled with concentration fluctuations. © 1990, American Chemical Society. All rights reserved.