We discuss our work on simple aliphatic glass-forming monoalcohols at low temperatures, including experiments on specific heat, thermal conductivity, Brillouin scattering and x-ray diffraction. The family of simple monoalcohols is an interesting model system for exploring molecular glass-forming liquids, the low-temperature universal properties of glasses, and even the glass transition phenomenon itself. More specifically, we examine the role of the molecular aspect ratio in the kinetics of vitrification/crystallization, the reported appearance of particular cases of polymorphism (in ethanol) and polyamorphism (in butanol), and, especially, the influence of positional isomerism and the location of the hydrogen bond on the lattice dynamics and, therefore, on the universal low-temperature properties of glasses.

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In this work, we present new calorimetric and thermodynamic measurements conducted on pure ethanol for its two kinds of glass transition, namely the conventional or structural glass transition and also the dynamical freezing of the plastic crystal (PC) state into an orientationally‐disordered crystal (or glassy crystal), that are found to occur exactly at the same temperature (Tg ≈ 97 K) and with comparable discontinuities in the specific heat. We have studied the dependence of the corresponding fictive temperatures on the different cooling rates and/or thermal annealing processes followed. The apparent activation energy and the concomitant fragility index were thus calculated for each glassy phase of ethanol, finding that the PC is a stronger “glass former” than the supercooled liquid.

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International audienceIn this work we review and concurrently discuss earlier and recent experiments performed on simple aliphatic glass-forming monoalcohols at low temperatures. By doing this, we find an interesting model system to explore different relevant issues concerning molecular glass-forming liquids and even the glass transition phenomenon itself. They include the role played by the molecular aspect ratio in vitrification/crystallization kinetics, the reported appearance of particular cases of polymorphism and polyamorphism, and the influence of chemical isomerism and the location of the hydrogen bond on lattice dynamics and hence on low-temperature properties of glasses