Unveiling the strong dependence of the α-relaxation dispersion on mixing thermodynamics in binary glass-forming liquids. Issue 9 (3rd March 2021)

• Record Type: Journal Article
• Authors: Liu, Xin; Li, Xudong; Wang, Ji; Feng, Shidong; Wang, Li-Min
• Is Part Of: Physical chemistry chemical physics. Volume 23:Issue 9(2021)
• Page Start: 5644
• Page End: 5651
• Publication Date: 2021-03-03
• Subjects: Chemistry, Physical and theoretical -- Periodicals; 541.3
• DOI: 10.1039/d0cp06358d
• Languages: English
• ISSNs: 1463-9076

Abstract

Abstract : The dynamic studies in binary molecular glass-forming mixtures with distinct mixing enthalpy revealed strong dependence of the structural α -relaxation dispersion on mixing thermodynamics using enthalpy and dielectric relaxation measurements. Abstract : Structural α -relaxation dispersion in binary molecular glass forming mixtures with distinct mixing enthalpy Δ H mix was investigated using enthalpic and dielectric relaxation measurements across the entire composition range. This study focused on the dependence of the relaxation dispersion on the mixing thermodynamics by determining the non-exponential exponent β, and its composition dependence. The β values determined by the enthalpic and dielectric relaxations agree well. Remarkably, it is found that the systems with positive enthalpy of mixing (exothermic, Δ H mix >0) have positive deviations in the composition dependence of β from the linear averaging of the two β values of the pure components, while negative deviations are observed for the systems with negative enthalpy of mixing (endothermic, Δ H mix <0). Furthermore, the relation between the non-exponential behaviors and entropy of mixing is discussed, revealing that the positive or negative deviation of β in its composition dependence on mixing is accompanied by the same sign of the excess entropy of mixing relative to the ideal one.