Why does low surface energy imply hydrophobicity?

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Discussion Overview

The discussion revolves around the relationship between surface energy and hydrophobicity, specifically exploring the microscopic processes that explain why materials with low surface energy tend to be hydrophobic. Participants seek a deeper understanding of the interactions between solid surfaces and liquids, including the role of bonding and interface energy.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant expresses confusion about the connection between low surface energy and hydrophobicity, seeking a microscopic explanation rather than phenomenological accounts.
  • Another participant suggests that if the surface energy between a solid and air is low, replacing air with a liquid is likely to increase the surface energy, implying a relationship between surface energy and wetting behavior.
  • A participant questions the nature of bonding between metals and liquids, indicating a need for clarification on how these interactions differ from traditional chemical bonds.
  • A later reply references an external source that discusses how interface energy is influenced by both short- and long-range forces, hinting at a complex interplay of factors affecting hydrophobicity.

Areas of Agreement / Disagreement

The discussion does not appear to reach a consensus, as participants express varying levels of understanding and propose different aspects of the relationship between surface energy and hydrophobicity.

Contextual Notes

Participants note limitations in existing explanations, highlighting a lack of detailed understanding of the microscopic processes and the specific nature of bonding interactions involved.

voila
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I don't understand why materials with low surface energy are hydrophobic and viceversa. All I can find are quick phenomenological explanations that don't quite deal with the physical (microscopic) process going on.

Could anyone provide a good microscopic picture of why it is that way? What's the role of the bonds in the material and how does it interact with the liquid to make it (or not) spread?
 
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It's just that if the surface energy between a solid and air is unusually small, it's more likely that replacing the air with a liquid will make the surface energy larger.
 
@hilbert2 Say you have a metal surface. How are the bondings between the metal and the liquid?
 
voila said:
@hilbert2 Say you have a metal surface. How are the bondings between the metal and the liquid?

They are not described in the same way how actual chemical bonds are described. There's a quite good explanation here how the interface energy depends on short- and long-range forces: http://www-f1.ijs.si/~rudi/sola/seminar_surface_tension.pdf .
 
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