Issue 2, 2024

Understanding the “Berg limit”: the 65° contact angle as the universal adhesion threshold of biomatter

Abstract

Surface phenomena in aqueous environments such as long-range hydrophobic attraction, macromolecular adhesion, and even biofouling are predominantly influenced by a fundamental parameter—the water contact angle. The minimal contact angle required for these and related phenomena to occur has been repeatedly reported to be around 65° and is commonly referred to as the “Berg limit.” However, the universality of this specific threshold across diverse contexts has remained puzzling. In this perspective article, we aim to rationalize the reoccurrence of this enigmatic contact angle. We show that the relevant scenarios can be effectively conceptualized as three-phase problems involving the surface of interest, water, and a generic oil-like material that is representative of the nonpolar constituents within interacting entities. Our analysis reveals that attraction and adhesion emerge when substrates display an underwater oleophilic character, corresponding to a “hydrophobicity under oil”, which occurs for contact angles above approximately 65°. This streamlined view provides valuable insights into macromolecular interactions and holds implications for technological applications.

Graphical abstract: Understanding the “Berg limit”: the 65° contact angle as the universal adhesion threshold of biomatter

Article information

Article type
Perspective
Submitted
19 Oct 2023
Accepted
08 Dec 2023
First published
12 Dec 2023
This article is Open Access
Creative Commons BY license

Phys. Chem. Chem. Phys., 2024,26, 713-723

Understanding the “Berg limit”: the 65° contact angle as the universal adhesion threshold of biomatter

M. Kanduč, E. Schneck and R. R. Netz, Phys. Chem. Chem. Phys., 2024, 26, 713 DOI: 10.1039/D3CP05084J

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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