Why are water-hydrophobic interfaces charged?

Konstantin N. Kudin, Roberto Car

Research output: Contribution to journalArticlepeer-review

203 Scopus citations


We report ab initio molecular dynamics simulations of hydroxide and hydronium ions near a hydrophobic interface, indicating that both ions behave like amphiphilic surfactants that stick to a hydrophobic hydrocarbon surface with their hydrophobic side. We show that this behavior originates from the asymmetry of the molecular charge distribution which makes one end of the ions strongly hydrophobic while the other end is even more hydrophilic than the regular water (H2O) molecules. The effect is more pronounced for the hydroxide than for the hydronium. Our results are consistent with several experimental observations and explain why hydrophobic surfaces in contact with water acquire a net negative charge, a phenomenon that has important implications for biology and polymer science.

Original languageEnglish (US)
Pages (from-to)3915-3919
Number of pages5
JournalJournal of the American Chemical Society
Issue number12
StatePublished - Mar 26 2008

All Science Journal Classification (ASJC) codes

  • General Chemistry
  • Biochemistry
  • Catalysis
  • Colloid and Surface Chemistry


Dive into the research topics of 'Why are water-hydrophobic interfaces charged?'. Together they form a unique fingerprint.

Cite this