### Abstract

Interfacial energy γ_{1,2} of a liquid-liquid or solid-liquid system is of paramount importance in colloid and interface science and its applications. To assess the dependence of γ_{1,2} on the surface energies γ_{1} and γ_{2} of two materials in contact, Girifalco and Good proposed their venerable equation involving the interfacial interaction parameter ϕ. Subsequently, values of ϕ have been experimentally determined for various material pairs. Here, we show that, the data of ϕ closely follow a unique relationship ϕ = (1 − γ_{1,2}/γ_{1})^{½} for all pairs where the other material is non-polar. Theoretically, this curve describes the smallest possible ϕ. However, we also show that substituting this relationship into the Girifalco-Good equation reduces it to Antonov's rule γ_{1,2} = γ_{1}−γ_{2}. Such a simplistic approach is inaccurate, and we conclude that the plotting of ϕ vs. γ_{1,2} has contributed to overestimating the applicability of the Girifalco-Good Equation.

Original language | English |
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Pages (from-to) | 243-246 |

Number of pages | 4 |

Journal | Journal of Colloid and Interface Science |

Volume | 529 |

DOIs | |

Publication status | Published - 1 Nov 2018 |

MoE publication type | A1 Journal article-refereed |

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### Keywords

- Equation of state
- Girifalco-Good equation
- Interfacial energy
- Interfacial interaction parameter
- Interfacial tension