On the glass transition in mixtures between the normal alcohols and various Lewis bases

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Abstract
The glass transition temperatures (Tg) of binary mixtures of the lower normal alkanols with several aprotic Lewis bases have been measured as a function of composition. The initial molar slope (IMS) at the pure alcohol end of the curve of Tg against mole fraction of base was accurately determined for each base. A related quantity, the reduced IMS, is shown to be proportional to the excess configurational entropy per bead of base introduced into dilute solution with the base. The reduced IMS is found to be a linear function of the length of the alcohol backbone for the heavier alkanols and to be an increasing function of the base Tg. The results are interpreted in terms of alcohol and base self‐association. Some form of network association is suggested for the lighter alkanols in the supercooled liquid, while the bases most likely associate under the action of dipole–dipole or other specific nonhydrogen bonding forces. The reduced IMS values suggest association between alcohol and base, but this association usually does not seem to be by means of hydrogen bonding in solutions dilute in the base. The Tg values of concentrated base solutions in the alcohols are discussed as well.