Decoupling between the Interfacial and Core Molecular Dynamics of Salol in 2D Confinement
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- 作者：Karolina Adrjanowicz ; Karolina Kolodziejczyk ; Wycliffe Kiprop Kipnusu ; Magdalena Tarnacka ; Emmanuel Urandu Mapesa ; Ewa Kaminska ; Sebastian Pawlus ; Kamil Kaminski ; Marian Paluch
- 刊名：Journal of Physical Chemistry C
- 出版年：2015
- 出版时间：June 25, 2015
- 年：2015
- 卷：119
- 期：25
- 页码：14366-14374
- 全文大小：447K
- ISSN：1932-7455
文摘
Dielectric spectroscopy and differential scanning calorimetry (DSC) were applied to study the molecular dynamics and thermal properties of a low-molecular-weight glass-forming liquid, salol (phenyl salicylate), confined in anodic aluminum oxide membranes of different pore diameters (100鈥?3 nm). On increasing the geometrical confinement, the glass transition temperature shifts toward lower temperatures, while at the same time broadening of the shape of the structural relaxation is observed. This was attributed to the interplay between surface and confinement effects leading to the transition from Vogel鈥揊ulcher鈥揟ammann-like to Arrhenius-like dependence of the structural relaxation times. We have noticed that the temperature of such crossover agrees with the endothermic process detected by DSC. Combined dielectric and calorimetric data have indicated that this phenomenon is related to the decoupling of the dynamics of molecules attached to the pore walls and those at the center. The enhancement of the structural relaxation of the core molecules increases with decreasing pore size possibly due to changes in the packing density. This finding gives a new insight into the behavior of glass-forming liquids under confinement and helps in the understand of the characteristic shift of the dynamic glass transition temperature with decreasing of the pore diameter.