Impact of Nanostructurization of the Pore Walls on the Dynamics of a Series of Phenyl Alcohols Incorporated within Nanoporous Aluminum Oxide Templates

Abstract

Herein, we studied the impact of surface roughness on the molecular dynamics of a series of phenyl-terminated monohydroxyalcohols under spatial confinement provided by nanoporous anodic aluminum oxide (AAO) membranes of constant (const-AAO) and modulated (modul-AAO) pore diameter using Broadband Dielectric Spectroscopy and Differential Scanning Calorimetry. Interestingly, we observed that both types of AAO membranes affect the behavior of examined associating materials in a different manner. Calorimetric measurements showed that the double glass transition phenomenon, commonly reported for many compounds infiltrated into const-AAO membranes, is not observed in the case of modul-AAO templates, where a single glass transition temperature was detected. Consequently, the dynamics of the dominant process was bulk-like in the whole range of studied temperatures for the samples infiltrated into the latter templates. Moreover, the Debye character of the dominant relaxation process characteristic for bulk samples was lost for the confined samples. Interestingly, the width of the dominant mode was the greatest in the alcohols infiltrated into modulated pores. It was assigned to the higher heterogeneity in the mobility introduced by the nanostructurization of the interface. The presented data emphasize the crucial impact of modulated-induced surface roughness of an applied constrained medium on the dynamics and phase transition of the liquids infiltrated into pores.