Correlating structural recovery in colloidal and molecular glasses

Jammed colloidal systems are considered as models of glass transition in molecular systems. McKenna and coworkers [1] tested this by comparing the structural recovery (physical aging) behavior in the two systems. Structural recovery in molecular glasses is well established by the three experiments suggested by Kovacs. However, the behavior from thermosensitive colloids following the Kovacs type histories were found to be vastly different. The present modelling work is carried out to figure whether the disagreements in results were due to fundamentally different aging behavior or due to differences in aging conditions/parameters in the two systems. TNM-KAHR framework is used to model the structural recovery in molecular systems in isobaric and isochoric conditions. We show that a molecular system aging under constant volume conditions following a simultaneous volume and temperature jump qualitatively mimics the structural recovery in colloidal glasses. Similarities between the model and the colloidal results suggest isochoric aging is a better analogue to structural recovery in colloids than the conventional isobaric conditions.

[1] Peng and McKenna. Phys. Rev. E (2016)