Influence of confinement on solvation of ethanol in water studied by Raman spectroscopy

Abstract

Herewith we present the results of our studies on the effect of confinement on the solvation of ethyl alcohol in aqueous solutions using Raman spectroscopy of the O-H stretching band. Based on Gaussian-Lorentzian deconvolution of the O-H band Raman spectra we investigate the local structures created between water-water, water-alcohol, and alcohol-alcohol molecules, which are directly related to the solubility of the liquids. Comparison of the responses in bulk solutions and in solutions confined in the pores of the gelatin gel shows that for high ethanol concentrations solubility significantly increases with decrease of the pore sizes.

Electrospinning of bioactive polycaprolactone-gelatin nanofibres with increased pore size for cartilage tissue engineering applications

“…40 Indeed, upon first contact with high concentration ethanol solutions, GEL stablishes bonds with ethanol molecules, creating ethanol sandwich clusters with the layer of water molecules inside, which ultimately leads to fiber dispersion, and preservation of the fibrous structure. 41 This way GEL fiber fusion as well as rapid and excessive GEL dissolution can be prevented, 31 which in fact was confirmed by the biodegradation studies on the PCL+GEL (Figure S2). The dissolved amount of GEL was lower (∼ 40%) on the PCL+GEL scaffolds subjected to the ethanol hydration treatment compared to the PCL+GEL controls, immersed only in PBS (∼ 50%) (Figure S2(a)).…”

Concentration selective hydration and phase states of hydroxyethyl cellulose (HEC) in aqueous solutions

“…These peaks are located at 3200, 3300 and 3460 cm −1 which were identified as follows [20]: (i) the peak around 3200 cm −1 arises from in phase vibration of, structurally arranged water, which is sometimes referred to as ice-like structures; (ii) the origin of the Raman peak around 3300 cm −1 in the water spectra appears from the OH stretching of partially structured water molecules wave number/ (cm -1 ) (liquid-like water) and (iii) the peak around 3460 cm −1 arises from poorly H-bonded water molecules (amorphous water). The water spectra could not be fitted to more than three Gaussian-Lorentzian functions unlike what was reported by Gadomska and Gadomski earlier [21,22]. Deconvolution of the raw spectra, to resolve the peaks, was done using Origin 6.1 software.…”

Bloß keinen Schnaps zum Lebkuchen

“…Die Mischbarkeit von Ethanol mit Wasser ist – makroskopisch betrachtet – unbegrenzt möglich, wobei diese ‚homogene‘ Beobachtung auf submikroskopischer Ebene schon bei geringen Mischungsgraden relativiert werden muss : Es kommt zu einer nur unvollständigen Durchmischung, in der es mit steigendem Ethanolanteil zum Nebeneinander von größeren Wasser‐ und Ethanolclustern kommt. Nur bei sehr hoher Verdünnung von Ethanol in Wasser ist davon auszugehen, dass Ethanolmoleküle stöchiometrisch exakt durch Wassermoleküle solvatisiert werden.…”