Revealing microheterogeneities and second order phase transitions in aqueous mixtures of 1-propoxypropan-2-ol at 298 K

Abstract

Second order phase transitions corresponding to discontinuities in the plots of Kirkwood-Buff integrals as a function of composition were observed in aqueous mixtures of the amphiphilic molecule, 1-propoxypropan-2-ol, revealing the formation of hydrophobic aggregates and generating microheterogeneities over a limited range of compositions. Electrospray mass spectra, surface tension measurements and solvatochromic parameters confirmed the onsets of different aggregation patterns over the entire composition range, and allowed us to scrutinize the prevailing types of aggregate species. This is seemingly the first time that such discontinuities are clearly assumed as second order phase transitions in a system macroscopically homogeneous and corroborated by other independent tools.

New Insights on Molecular Interactions in the Aqueous Systems (3-Ethoxy or 3-Butoxy)propan-1-amine Mixtures Using Refractive Indices and Molecular Probes

“…Numerous notable papers have been published dedicated to the study of the enigmatic aqueous amphiphilic mixtures, accurately measuring thermodynamic, acoustic, and spectroscopic properties, namely, density, sound speed, enthalpy, heat capacity, neutron diffraction, mass spectroscopy, and maximum wavelengths of molecular probes, among others. − Derived properties such as excess molar, partial molar, and their derivatives have been providing important keys to deepen our understanding of molecular interactions, especially in the perturbation of water structure caused by the introduction of a solute into water. − …”