Fluid–wall interactions effects on the dynamical properties of confined orthoterphenyl

• Published in: Journal of non-crystalline solids Vol. 352; no. 42-49; pp. 4964 - 4968
• Main Authors: Dosseh, Gilberte, Le Quellec, Christelle, Brodie-linder, Nancy, Alba-simionesco, Christiane, Haeussler, Wolfgang, Levitz, Pierre
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Amsterdam Elsevier B.V 15.11.2006; Elsevier
• Subjects: Chemical Physics; Condensed matter: structure, mechanical and thermal properties; Equations of state, phase equilibria, and phase transitions; Exact sciences and technology; Glass transitions; Physics; Specific phase transitions; Structural relaxation; Structural relaxation; Terphenyl derivatives; Pore size; Temperature effects; Surface properties; Dynamic properties; Spin echo; Nanoporous materials; Nuclear magnetic resonance; Surface layers; Structure relaxation; Glass formation
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/j.jnoncrysol.2006.02.160

We have investigated the dynamics of fragile glass forming orthoterphenyl confined in nanoporous materials with different surface properties. The dynamics on the nanosecond timescale were probed with neutron spin echo measurements. The intermediate scattering functions were fitted using a stretched exponential and a background. This background, due to molecules forming an interfacial layer at the surface of the pore that are immobile at the nanosecond time scale, depends on the surface properties of the porous materials and increases with decreasing temperature. The dynamics of the confined liquid depends on fluid–wall interactions: the dynamics are slower in a weakly attractive silica-walled material with 7.1nm pores (∼9 molecular diameters) than in a hydrophobic material with 6.3nm pores (∼8 molecular diameters). Adsorption times of 1μs and 690ns at 298 and 323K for oTP confined in silica-walled nanoporous materials were calculated from nuclear magnetic resonance field cycling relaxometry experiments.