Small activation entropy bestows high-stability of nanoconfined D-mannitol

• 作者: Lin Cao Li-Jian Song Ya-Ru Cao Wei Xu Jun-Tao Huo Yun-Zhuo Lv Jun-Qiang Wang
• 来源期刊: 中国物理B（英文版）
• 年，卷（期）: 2021,（7）
• 所属期刊栏目: CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROP-ERTIES
• 页码范围: 426-432
• 页数: 7页
• 语种: 英文
• DOI: 10.1088/1674-1056/abf919

摘要

It has been a long-standing puzzling problem that some glasses exhibit higher glass transition temperatures (denoting high stability) but lower activation energy for relaxations (denoting low stability).In this paper,the relaxation kinetics of the nanoconfined D-mannitol (DM) glass was studied systematically using a high-precision and high-rate nanocalorimeter.The nanoconfined DM exhibits enhanced thermal stability compared to the free DM.For example,the critical cooling rate for glass formation decreases from 200 K/s to below 1 K/s;the Tg increases by about 20 K-50 K.The relaxation kinetics is analyzed based on the absolute reaction rate theory.It is found that,even though the activation energy E* decreases,the activation entropy S* decreases much more for the nanoconfined glass that yields a large activation free energy G* and higher thermal stability.These results suggest that the activation entropy may provide new insights in understanding the abnormal kinetics of nanoconfined glassy systems.