Liquid-liquid interfaces of semifluorinated alkane diblock copolymers with water, alkanes, and perfluorinated alkanes.
The liquid-liquid interface between semifluorinated alkane diblock copolymers of the form F3C(CF2)n-1-(CH2)m-1CH3 and water, protonated alkanes, and perfluorinated alkanes are studied by fully atomistic molecular dynamics simulations. A modified version of the OPLS-AA (Optimized Parameter for Liquid Simulation All-Atom) force field of Jorgensen et al. has been used to study the interfacial behavior of semifluorinated diblocks. Aqueous interfaces are found to be sharp, with correspondingly large values of the interfacial tension. Due to the reduced hydrophobicity of the protonated block compared to the fluorinated block, hydrogen enhancement is observed at the interface. Water dipoles in the interfacial region are found to be oriented nearly parallel to the liquid-liquid interface. A number of protonated alkanes and perfluorinated alkanes are found to be mutually miscible with the semifluorinated diblocks. For these liquids, interdiffusion follows the expected Fickian behavior, and concentration-dependent diffusivities are determined.
Department of Chemistry, Clemson University, Clemson, South Carolina 29634, USA. fpierce@clemson.edu
Flint
F
Pierce
Mesfin
M
Tsige
Dvora
D
Perahia
Gary S
GS
Grest
D000473:Alkanes / Q000737:chemistry*; D003198:Computer Simulation; D017611:Fluorine Compounds / Q000737:chemistry*; D008958:Models, Molecular; D011108:Polymers / Q000737:chemistry*; D011522:Protons; D013997:Time Factors; D014867:Water / Q000737:chemistry*
D000473:Alkanes; D017611:Fluorine Compounds; D011108:Polymers; D011522:Protons; D014867:Water