Résumé
Glassy state is often observed in materials science, but is also crucial in geology, biology, pharmacopoeia, or foods processing...The glassy state is usually obtained by cooling a system from the liquid state, for which the molecular mobility is important, to low temperature, at which the system can be considered as a solid obtained by avoiding the crystallization process. The glass transition corresponds to the temperature at which the system can be considered as frozen on the time scale of the experiment. Although this phenomenon is ubiquitious in nature and known for a long time, the molecular process by which liquids acquire rigidity upon cooling remain an open question in condensed matter science. This glass transition phenomenon, which is not a classical phase transition, is associated with both thermodynamics and kinetics processes, which are described in this paper.