title: Hydrophobicity vs hydrophilicity: Effects of poly(ethylene glycol) and tert-butyl alcohol on H2O as probed by 1-propanol.
abstract: The enthalpic interaction between 1-propanol (1P) molecules, , was evaluated in 1P-poly(ethylene glycol) (PEG)-H2O and 1P-tert-butyl alcohol (TBA)-H2O ternary mixtures. The model-free and experimentally accessible quantity, , indicates the effect of an additional 1P on the actual enthalpic situation of 1P in the mixture. It was shown earlier that the composition dependence of reflects the process how 1P modifies H2O. This pattern changes in the presence of a third component, PEG or TBA. The effects of PEG or TBA on the molecular organization of H2O were elucidated from these induced changes. Together with previous similar studies for the effects of methanol (ME), 2-propanol (2P), ethylene glycol (EG), and glycerol (Gly), we suggest a method and hence a possible scaling for sorting out hydrophobicity vs hydrophilicity of these alcohols by the changes induced to the loci of the maxima in . We show that hydrophilicity scales with the number of oxygen, regardless of whether O is the ether -O- or the hydroxyl -OH. Hydrophobicity also scales with the number of carbon atoms for alcohols without a methyl group. For those with methyl groups, the hydrophobicity seems proportional to the total number of carbon with a different proportionality factor from those without methyl group.
authors.affiliation: Department of Liberal Arts and Basic Sciences, College of Industrial Technology, Nihon University, Narashino, Chiba 275-8575, Japan.
authors.forename: Kumiko
authors.initials: K
authors.lastname: Miki
authors.forename: Peter
authors.initials: P
authors.lastname: Westh
authors.forename: Yoshikata
authors.initials: Y
authors.lastname: Koga
mesh_terms: D000433:1-Propanol / Q000737:chemistry*; D019840:2-Propanol / Q000737:chemistry; D000465:Algorithms; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D019855:Ethylene Glycol / Q000737:chemistry; D005990:Glycerol / Q000737:chemistry; D015335:Molecular Probes; D011092:Polyethylene Glycols / Q000737:chemistry*; D013816:Thermodynamics; D014867:Water / Q000737:chemistry*; D020002:tert-Butyl Alcohol / Q000737:chemistry*
chemical_list: D015335:Molecular Probes; D014867:Water; D011092:Polyethylene Glycols; D000433:1-Propanol; D019855:Ethylene Glycol; D020002:tert-Butyl Alcohol; D019840:2-Propanol; D005990:Glycerol