The Experts below are selected from a list of 36 Experts worldwide ranked by ideXlab platform
A.w. Neumann - One of the best experts on this subject based on the ideXlab platform.
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Study of the advancing and receding contact angles: Liquid sorption as a cause of contact angle hysteresis.
Advances in Colloid and Interface Science, 2002Co-Authors: C.n.c Lam, Michael L. Hair, A.w. NeumannAbstract:Two types of experiments were used to study the behavior of both advancing and receding contact angles, namely the dynamic one-cycle contact angle (DOCA) and the dynamic cycling contact angle (DCCA) experiments. For the preliminary study, DOCA measurements of different Liquids on different solids were performed using an automated axisymmetric drop shape analysis-profile (ADSA-P). From these experimental results, four patterns of receding contact angle were observed: (1) time-dependent receding contact angle; (2) constant receding contact angle; (3) 'stick/slip'; (4) no receding contact angle. For the purpose of illustration, results from four different solid surfaces are shown. These solids are: FC-732-coated surface; poly(methyl methacrylate/n-butyl methacrylate) [P(MMA/nBMA)]; poly(lactic acid) (DL-PLA); and poly(lactic/glycolic acid) 50/50 (DL-PLGA 50/50). Since most of the surfaces in our studies exhibit time dependence in the receding contact angle, a more extended study was conducted using only FC-732-coated surfaces to better understand the possible causes of decreasing receding contact angle and contact angle hysteresis. Contact angle measurements of 21 Liquids from two homologous series (i.e. n-alkanes and 1-alcohols) and octamethylcyclotetrasiloxane (OCMTS) on FC-732-coated surfaces were performed. It is apparent that the contact angle hysteresis decreases with the chain length of the Liquid. It was found that the receding contact angle equals the advancing angle when the alkane Molecules are infinitely large. These results strongly suggest that the chain length and size of the Liquid Molecule could contribute to contact angle hysteresis phenomena. Furthermore, DCCA measurements of six Liquids from the two homologous series on FC-732-coated surfaces were performed. With these experimental results, one can construe that the time dependence of contact angle hysteresis on relatively smooth and homogeneous surfaces is mainly caused by Liquid retention/sorption. The results also suggested that the contact angle hysteresis will eventually approach a steady state, where the rate of Liquid retention-evaporation or sorption process would balance out each other. If the existence of contact angle hysteresis can be attributed to Liquid sorption/retention, one should only use the advancing contact angles (measured on a dry surface) in conjunction with Young's equation for surface energetic calculations.
C.n.c Lam - One of the best experts on this subject based on the ideXlab platform.
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Study of the advancing and receding contact angles: Liquid sorption as a cause of contact angle hysteresis.
Advances in Colloid and Interface Science, 2002Co-Authors: C.n.c Lam, Michael L. Hair, A.w. NeumannAbstract:Two types of experiments were used to study the behavior of both advancing and receding contact angles, namely the dynamic one-cycle contact angle (DOCA) and the dynamic cycling contact angle (DCCA) experiments. For the preliminary study, DOCA measurements of different Liquids on different solids were performed using an automated axisymmetric drop shape analysis-profile (ADSA-P). From these experimental results, four patterns of receding contact angle were observed: (1) time-dependent receding contact angle; (2) constant receding contact angle; (3) 'stick/slip'; (4) no receding contact angle. For the purpose of illustration, results from four different solid surfaces are shown. These solids are: FC-732-coated surface; poly(methyl methacrylate/n-butyl methacrylate) [P(MMA/nBMA)]; poly(lactic acid) (DL-PLA); and poly(lactic/glycolic acid) 50/50 (DL-PLGA 50/50). Since most of the surfaces in our studies exhibit time dependence in the receding contact angle, a more extended study was conducted using only FC-732-coated surfaces to better understand the possible causes of decreasing receding contact angle and contact angle hysteresis. Contact angle measurements of 21 Liquids from two homologous series (i.e. n-alkanes and 1-alcohols) and octamethylcyclotetrasiloxane (OCMTS) on FC-732-coated surfaces were performed. It is apparent that the contact angle hysteresis decreases with the chain length of the Liquid. It was found that the receding contact angle equals the advancing angle when the alkane Molecules are infinitely large. These results strongly suggest that the chain length and size of the Liquid Molecule could contribute to contact angle hysteresis phenomena. Furthermore, DCCA measurements of six Liquids from the two homologous series on FC-732-coated surfaces were performed. With these experimental results, one can construe that the time dependence of contact angle hysteresis on relatively smooth and homogeneous surfaces is mainly caused by Liquid retention/sorption. The results also suggested that the contact angle hysteresis will eventually approach a steady state, where the rate of Liquid retention-evaporation or sorption process would balance out each other. If the existence of contact angle hysteresis can be attributed to Liquid sorption/retention, one should only use the advancing contact angles (measured on a dry surface) in conjunction with Young's equation for surface energetic calculations.
Michael L. Hair - One of the best experts on this subject based on the ideXlab platform.
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Study of the advancing and receding contact angles: Liquid sorption as a cause of contact angle hysteresis.
Advances in Colloid and Interface Science, 2002Co-Authors: C.n.c Lam, Michael L. Hair, A.w. NeumannAbstract:Two types of experiments were used to study the behavior of both advancing and receding contact angles, namely the dynamic one-cycle contact angle (DOCA) and the dynamic cycling contact angle (DCCA) experiments. For the preliminary study, DOCA measurements of different Liquids on different solids were performed using an automated axisymmetric drop shape analysis-profile (ADSA-P). From these experimental results, four patterns of receding contact angle were observed: (1) time-dependent receding contact angle; (2) constant receding contact angle; (3) 'stick/slip'; (4) no receding contact angle. For the purpose of illustration, results from four different solid surfaces are shown. These solids are: FC-732-coated surface; poly(methyl methacrylate/n-butyl methacrylate) [P(MMA/nBMA)]; poly(lactic acid) (DL-PLA); and poly(lactic/glycolic acid) 50/50 (DL-PLGA 50/50). Since most of the surfaces in our studies exhibit time dependence in the receding contact angle, a more extended study was conducted using only FC-732-coated surfaces to better understand the possible causes of decreasing receding contact angle and contact angle hysteresis. Contact angle measurements of 21 Liquids from two homologous series (i.e. n-alkanes and 1-alcohols) and octamethylcyclotetrasiloxane (OCMTS) on FC-732-coated surfaces were performed. It is apparent that the contact angle hysteresis decreases with the chain length of the Liquid. It was found that the receding contact angle equals the advancing angle when the alkane Molecules are infinitely large. These results strongly suggest that the chain length and size of the Liquid Molecule could contribute to contact angle hysteresis phenomena. Furthermore, DCCA measurements of six Liquids from the two homologous series on FC-732-coated surfaces were performed. With these experimental results, one can construe that the time dependence of contact angle hysteresis on relatively smooth and homogeneous surfaces is mainly caused by Liquid retention/sorption. The results also suggested that the contact angle hysteresis will eventually approach a steady state, where the rate of Liquid retention-evaporation or sorption process would balance out each other. If the existence of contact angle hysteresis can be attributed to Liquid sorption/retention, one should only use the advancing contact angles (measured on a dry surface) in conjunction with Young's equation for surface energetic calculations.
Lirong Liu - One of the best experts on this subject based on the ideXlab platform.
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Thermodynamic phase behaviour and miscibility of confined fluids in nanopores
Chemical Engineering Journal, 2018Co-Authors: Kaiqiang Zhang, Na Jia, Lirong LiuAbstract:Abstract In this paper, thermodynamic phase behaviour and miscibility of confined pure and mixing fluids in nanopores are studied. First, a semi-analytical equation of state (EOS) is developed, based on which two correlations are modified to predict the shifts of critical temperature and pressure. Second, the thermodynamic free energy of mixing and solubility parameter are derived, quantitatively calculated, and applied to study the conditions and characteristics of the fluid miscibility in nanopores. Third, an improved EOS model with the modified correlations is proposed and used to calculate the phase properties and miscibility-associated quantities of three mixing fluids. The critical temperature and pressure of confined fluids are always decreased by reducing the pore radius. The negative pressure state is validated for a confined Liquid, whose upper temperature limit is quantitatively determined and found to be lowered with the reduction of pore radius. The Liquid–gas miscibility is beneficial from the pore radius reduction and the intermediate hydrocarbons (e.g., C2, C3, i- and n-C4) perform more miscible with the Liquid C8 in comparison with the lean gas (e.g., N2 and CH4). Moreover, the molecular diameter of single Liquid Molecule is determined to be the bottom limit, the pore radius above which is concluded as a necessary condition for the Liquid–gas miscibility. The calculated phase behaviour and minimum miscibility pressures (MMPs) of the three mixing fluids agree well with the literature results, which reveals that the shifts of critical properties dominate the phase behaviour and miscibility changes of confined fluids from bulk phase to nanopores.
Taku Ohara - One of the best experts on this subject based on the ideXlab platform.
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molecular dynamics investigation of surface roughness scale effect on interfacial thermal conductance at solid Liquid interfaces
Journal of Chemical Physics, 2019Co-Authors: Donatas Surblys, Yoshiaki Kawagoe, Masahiko Shibahara, Taku OharaAbstract:Non-equilibrium molecular dynamics simulations were conducted for solid-Liquid-solid systems with nanometer scale grooved surfaces and an induced heat flux for a wide range of topology and solid-Liquid interaction conditions to investigate the mechanism of solid-Liquid heat transfer, which is the first work of such extensive detail done about the nanoscale roughness effect on heat transfer properties. Single-atom Molecules were used for Liquid, and the solid-Liquid interaction was varied from superhydrophobic to superhydrophilic, while the groove scale was varied from single atom to several nanometers, while keeping the surface area twice that of a flat surface. Both Wenzel and Cassie wetting regimes with a clear transition point were observed due to the capillary effect inside larger grooves that were more than 5 Liquid Molecule diameters, while such transition was not observed at smaller scales. At the hydrophobic state, large scale grooves had lower interfacial thermal conductance (ITC) due to the Cassie regime, i.e., having unfilled grooves, while at the hydrophilic state, grooved surfaces had ITC about twice that of a flat surface, indicating an extended heat transfer surface effect regardless of the groove scale. At the superhydrophilic state, crystallization of Liquid at the surface occurred, and the packing of Liquid Molecules had a substantial effect on ITC regardless of the groove scale. Finally, both potential energy of solid-Liquid interaction and work of solid-Liquid adhesion were calculated and were shown to be in similar relations to ITC for all groove scales, except for the smallest single-atom scale grooves, due to a different heat transfer mechanism.