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Secondary relaxation in ultrastable etoricoxib: evidence of correlation with structural relaxation

2018; Royal Society of Chemistry; Volume: 20; Issue: 6 Linguagem: Inglês

10.1039/c7cp06445d

1463-9084

Cristian Rodríguez-Tinoco, Marzena Rams‐Baron, K. L. Ngai, Karolina Jurkiewicz, J. Rodríguez‐Viejo, Marian Paluch,

Liquid Crystal Research Advancements

Secondary relaxations are fundamental for their impact in the properties of glasses and for their inseparable connection to the structural relaxation. Understanding their density dependence and aging behavior is key to fully address the nature of glasses. Ultrastable glasses establish a new benchmark to study the characteristics of secondary relaxations, since their enthalpy and density levels are unattainable by other routes. Here, we use dielectric spectroscopy at ambient and elevated pressures to study the characteristics of the secondary relaxation in ultrastable etoricoxib, reporting a 71% decrease in dielectric strength and one decade increase in relaxation time compared to the ordinary glass. Interestingly, we find an unprecedented connection between secondary and structural relaxations in ultrastable etoricoxib in exactly the same manner as in the ordinary glass, manifested through different properties, such as aging and devitrification. These results further support and extend the general validity of the connection between the secondary and structural relaxation.