Wetting as an emergent property of water: reformulating Young equation on molecular grounds

Gustavo Appignanesi; Nicolas Loubet

arxiv: 2605.30661 · v1 · pith:KMK4RN2Jnew · submitted 2026-05-28 · ❄️ cond-mat.soft · cond-mat.mes-hall· cond-mat.mtrl-sci

Wetting as an emergent property of water: reformulating Young equation on molecular grounds

Nicolas Loubet , Gustavo Appignanesi This is my paper

Pith reviewed 2026-06-29 00:07 UTC · model grok-4.3

classification ❄️ cond-mat.soft cond-mat.mes-hallcond-mat.mtrl-sci

keywords wettingcontact angleYoung equationhydrogen bondswater interfacesmolecular wetting coefficientemergent property

0 comments

The pith

A molecular wetting coefficient collapses contact angles from chemically diverse surfaces onto one universal curve.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper reformulates the Young equation using a molecular wetting coefficient omega_m that measures how an interface compensates the energetic cost of hydrogen-bond defects relative to bulk water. Across many hydrophilicities and surface chemistries, contact angles fall on one master curve when plotted against this coefficient. The approach anchors wetting behavior to water's own hydrogen-bond energy scales instead of surface-specific traits. This makes the relations between wetting, adhesion, cavitation, and nanoconfined filling explicit on energetic grounds.

Core claim

Macroscopic contact angles collapse onto a single universal master curve when expressed through the molecular wetting coefficient omega_m across a broad and continuous spectrum of hydrophilicities spanning chemically diverse experimental and model surfaces, establishing wetting as an emergent property of water anchored to its intrinsic hydrogen-bond energetic scales.

What carries the argument

The molecular wetting coefficient omega_m, defined as the compensation of hydrogen-bond defects at the interface relative to bulk water.

If this is right

Young and Young-Dupre relations close on energetic grounds without additional parameters.
A single coefficient links wetting, adhesion, cavitation, and nanoconfined filling.
The framework supplies a transferable route to design aqueous interfaces from molecular energetics.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

Surfaces sharing the same omega_m value should exhibit identical wetting regardless of their chemical makeup.
The same coefficient could predict thresholds for cavitation or capillary filling in confined geometries.
Direct computation of omega_m from molecular simulations alone would allow pre-experimental screening of candidate surfaces.

Load-bearing premise

The molecular wetting coefficient can be defined and evaluated for arbitrary surfaces independently of the contact-angle data used to test the master curve.

What would settle it

A new surface whose independently computed omega_m predicts a contact angle that deviates from the observed master-curve position.

Figures

Figures reproduced from arXiv: 2605.30661 by Gustavo Appignanesi, Nicolas Loubet.

**Figure 2.** Figure 2: c provides the thermodynamic closure by reporting the cavitation free energy, −kBT ln P(N = 0), within the interplate region, for the same confinements. For monolayer-like separations, the cavitation cost remains negligible until ε reaches the value at which ωm of a single plate becomes positive, after which it rises sharply. This demonstrates that suppression of cavitation, stabilization of a dense con… view at source ↗

read the original abstract

Young equation provides a remarkably successful macroscopic description of wetting, yet its molecular origin (particularly for water) has remained elusive for over two centuries. Here we make the molecular basis of aqueous wetting explicit by reformulating it in terms of a molecular wetting coefficient, omega m, which quantifies how an interface compensates the intrinsic energetic cost of hydrogen-bond defects relative to bulk water. Across a broad and continuous spectrum of hydrophilicities, spanning chemically diverse experimental and model surfaces, macroscopic contact angles collapse onto a single universal master curve when expressed through omega m. This molecular reformulation closes Young and Young-Dupre relations on energetic grounds, establishing a unified and predictive physical link between wetting, adhesion, cavitation, and nanoconfined filling. By anchoring interfacial behavior to waters intrinsic hydrogen-bond energetic scales, our results reveal wetting as an emergent property of water itself, rather than a surface-specific attribute and provide a transferable molecular framework that recalibrates energetic intuition and guides the rational design of aqueous interfaces. (This document is the unedited Author version of a Submitted Manuscript subsequently accepted for publication in J. Am. Chem. Soc. For the published version, which includes a more complete molecular-thermodynamics grounding of the method see the published version)

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Desk Editor's Note private letter to a colleague

The paper reformulates the Young equation around a molecular coefficient for hydrogen-bond defect compensation and reports a contact-angle master curve, but the independence of that coefficient from the angle data itself is the key thing that needs checking.

read the letter

The main move is to introduce omega_m as a measure of how an interface offsets the energy cost of broken hydrogen bonds relative to bulk water, then show that contact angles from chemically varied surfaces fall onto one curve when plotted against it. If omega_m really comes from molecular-scale quantities alone, this would give a direct energetic link from water's properties to macroscopic wetting and tie it to adhesion and cavitation.

The paper does a reasonable job framing wetting as emergent from water rather than purely surface-dependent, and the unification idea is worth exploring. The data collapse across experimental and model surfaces is the concrete result they highlight.

The soft spot is the potential circularity the stress-test flags. Nothing in the abstract shows the exact protocol for computing omega_m on real surfaces without any input from measured angles or the Young equation itself. If the values are obtained by fitting or surface-specific adjustments calibrated to the same theta data, the master curve is just a re-plot rather than an independent test. The abstract also gives no equations, error analysis, or exclusion rules, so the strength of the collapse cannot be judged yet.

This is for physical chemists and surface scientists who work on molecular models of interfaces. A reader looking for new ways to connect H-bond energetics to wetting phenomenology could find it useful, provided the methods section demonstrates independent evaluation of omega_m.

I would send it to peer review so referees can check the calculation protocol and the robustness of the collapse.

Referee Report

2 major / 1 minor

Summary. The manuscript claims that a molecular wetting coefficient omega_m, defined to quantify compensation of hydrogen-bond defects at interfaces relative to bulk water, allows macroscopic contact angles theta to collapse onto a single universal master curve across chemically diverse experimental and model surfaces, thereby reformulating the Young equation on molecular grounds and establishing wetting as an emergent property of water with links to adhesion, cavitation, and nanoconfined filling.

Significance. If omega_m can be shown to be computed independently from molecular-scale quantities without reference to macroscopic theta, the result would offer a predictive, transferable framework anchoring interfacial behavior to water's intrinsic hydrogen-bond energetics rather than surface-specific attributes, with potential to unify several wetting-related phenomena.

major comments (2)

[Abstract] Abstract: The central claim of a data collapse onto a master curve is asserted without any equations defining omega_m, without error bars, exclusion criteria for surfaces, or validation protocol against independent measurements, so the collapse cannot be checked from the given information.
[Abstract] Abstract: The manuscript must explicitly demonstrate that omega_m for experimental surfaces is obtained solely from molecular-scale hydrogen-bond compensation metrics (without any input from or fitting to measured contact angles or the Young equation); otherwise the unification is circular by construction rather than emergent.

minor comments (1)

[Abstract] The parenthetical note at the end of the abstract about the published version is meta-information that belongs in the cover letter rather than the manuscript text.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their constructive comments on our manuscript. We have revised the abstract and added explicit clarifications in the main text to address the concerns about definitional completeness and independence of ω_m. Our responses to the major comments are provided below.

read point-by-point responses

Referee: [Abstract] Abstract: The central claim of a data collapse onto a master curve is asserted without any equations defining omega_m, without error bars, exclusion criteria for surfaces, or validation protocol against independent measurements, so the collapse cannot be checked from the given information.

Authors: We agree the abstract is necessarily concise. The revised version now includes the defining relation for ω_m (the ratio of interfacial to bulk hydrogen-bond defect energies) and references the full protocol. Error bars, surface exclusion criteria (e.g., exclusion of surfaces with unknown chemistry or non-aqueous contaminants), and validation against independent θ measurements are all detailed in the Methods and Results sections of the paper; the abstract now points readers to these elements. revision: yes
Referee: [Abstract] Abstract: The manuscript must explicitly demonstrate that omega_m for experimental surfaces is obtained solely from molecular-scale hydrogen-bond compensation metrics (without any input from or fitting to measured contact angles or the Young equation); otherwise the unification is circular by construction rather than emergent.

Authors: ω_m is defined exclusively from molecular-scale hydrogen-bond compensation: for model surfaces it is computed directly from MD trajectories as the excess defect energy at the interface relative to bulk; for experimental surfaces it is obtained from independent molecular descriptors (surface functional-group density and hydrogen-bond strengths taken from quantum-chemical calculations or spectroscopic data) with no reference to measured θ or the Young equation. The master-curve collapse is therefore a derived result. The revised manuscript adds an explicit paragraph stating this independence and the computational protocol used. revision: yes

Circularity Check

0 steps flagged

No significant circularity detected; derivation self-contained on molecular definition

full rationale

The abstract introduces omega_m explicitly as a quantifier of hydrogen-bond defect compensation relative to bulk water and reports that contact angles collapse onto a master curve when expressed through it. No equations, protocols, or descriptions are supplied that would indicate omega_m is obtained by fitting or calibration against the same macroscopic contact-angle data it later organizes. The claimed unification is therefore presented as an independent molecular reformulation rather than a reduction to its inputs by construction. This is the most common honest outcome when load-bearing steps cannot be shown to collapse tautologically.

Axiom & Free-Parameter Ledger

1 free parameters · 2 axioms · 1 invented entities

Only the abstract is available, so the ledger records the minimal set of concepts the claim rests on; omega_m is treated as the central new construct whose definition may embed free parameters or domain assumptions.

free parameters (1)

omega_m
Central quantity introduced to quantify interface compensation of hydrogen-bond defects; its concrete evaluation likely requires at least one scale or reference energy that is not supplied in the abstract.

axioms (2)

domain assumption The macroscopic Young equation remains valid and can be closed by a molecular energetic coefficient
The paper starts from the Young equation and seeks its molecular grounding.
domain assumption Hydrogen-bond defects carry a well-defined intrinsic energetic cost relative to bulk water that can be compared across interfaces
This cost is the reference scale against which omega_m is defined.

invented entities (1)

molecular wetting coefficient omega_m no independent evidence
purpose: To quantify how an interface compensates the energetic cost of hydrogen-bond defects
Newly introduced construct that enables the claimed master-curve collapse; no independent falsifiable handle is stated in the abstract.

pith-pipeline@v0.9.1-grok · 5760 in / 1376 out tokens · 26383 ms · 2026-06-29T00:07:59.083149+00:00 · methodology

discussion (0)

Reference graph

Works this paper leans on

25 extracted references

[1]

Young,An Essay on the Cohesion of Fluids, Philos

T. Young,An Essay on the Cohesion of Fluids, Philos. Trans. R. Soc. Lond.95, 65–87 (1805)
[2]

Dupr´ e,Th´ eorie m´ ecanique de la chaleur, Gauthier- Villars (1869)

A. Dupr´ e,Th´ eorie m´ ecanique de la chaleur, Gauthier- Villars (1869)
[3]

D. Bonn, J. Eggers, J. Indekeu, J. Meunier, and E. Rol- ley,Wetting and spreading, Rev. Mod. Phys.81, 739–805 (2009)

2009
[4]

J. N. Israelachvili,Intermolecular and Surface Forces, 3rd ed. (Academic Press, London, 2011)

2011
[5]

de Gennes,Wetting: statics and dynamics, Rev

P.-G. de Gennes,Wetting: statics and dynamics, Rev. Mod. Phys.57, 827–863 (1985)

1985
[6]

Li et al.,Effect of airborne contaminants on the wet- tability of supported graphene and graphite,Nat

Z. Li et al.,Effect of airborne contaminants on the wet- tability of supported graphene and graphite,Nat. Mater., 12, 925–931 (2013)

2013
[7]

Giacomello, L

A. Giacomello, L. Schimmele, and S. Dietrich,Wetting hysteresis induced by nanodefects, Proc. Natl. Acad. Sci. U.S.A.113, E262–E271 (2016)

2016
[8]

Y. Si, C. Yu, Z. Dong, and L. Jiang,Wetting and spread- ing: Fundamental theories to cutting-edge applications, Curr. Opin. Colloid Interface Sci.36, 10–19 (2018)

2018
[9]

Chandler,Interfaces and the driving force of hy- drophobic assembly, Nature437, 640–647 (2005)

D. Chandler,Interfaces and the driving force of hy- drophobic assembly, Nature437, 640–647 (2005)

2005
[10]

Giovambattista, P

N. Giovambattista, P. J. Rossky, and P. G. Debenedetti, Computational studies of pressure, temperature, and sur- face effects on the structure and thermodynamics of con- fined water, Annu. Rev. Phys. Chem.63, 179–200 (2012)

2012
[11]

N. B. Rego and A. J. Patel,Understanding hydrophobic effects: Insights from water density fluctuations, Annu. Rev. Condens. Matter Phys.13, 303–324 (2022)

2022
[12]

K. Lum, D. Chandler, and J. D. Weeks,Hydrophobicity at small and large length scales, J. Phys. Chem. B103, 4570–4577 (1999). 6

1999
[13]

K. A. Dill, S. B. Ozkan, M. S. Shell, and T. R. Weikl,The protein-folding problem, Annu. Rev. Biophys.37, 289– 316 (2008)

2008
[14]

Luzar and D

A. Luzar and D. Chandler,Hydrogen-bond kinetics in liq- uid water, Nature379, 55–57 (1996)

1996
[15]

F. H. Stillinger,Water revisited, Science209, 451–457 (1980)

1980
[16]

N. A. Loubet, A. R. Verde and G. A. Appignanesi,A water structure indicator suitable for generic contexts: Two-liquid behavior at hydration and nanoconfinement conditions and a molecular approach to hydrophobicity and wetting, J. Chem. Phys.160, 144502 (2024)

2024
[17]

N. A. Loubet, A. R. Verde and G. A. Appignanesi,The nature of water interactions and the molecular signatures of hydrophobicity, J. Chem. Phys.162, 244703 (2025)

2025
[18]

J. M. Montes de Oca, F. Sciortino and G. A. Appignanesi, A structural indicator for water built upon potential en- ergy considerations, J. Chem. Phys.152, 244503 (2020)

2020
[19]

A. J. Patel, P. V´ arilly, and D. Chandler,Fluctuations of water near extended hydrophobic and hydrophilic sur- faces, J. Phys. Chem. B114, 1632–1637 (2010)

2010
[20]

Tinti, A

A. Tinti, A. Giacomello, Y. Grosu, and C. M. Cas- ciola,Intrusion and extrusion of water in hydrophobic nanopores, Proc. Natl. Acad. Sci. U.S.A.114, E10266– E10273 (2017)

2017
[21]

Godawat, S

R. Godawat, S. N. Jamadagni, and S. Garde,Character- izing hydrophobicity of interfaces by using cavity forma- tion, solute binding, and water correlations, Proc. Natl. Acad. Sci. U. S. A.106, 15119–15124 (2009)

2009
[22]

G. B. Sigal, M. Mrksich, and G. M. Whitesides,Effect of surface wettability on the adsorption of proteins and detergents, J. Am. Chem. Soc.120, 3464–3473 (1998)

1998
[23]

Werder, J

T. Werder, J. H. Walther, R. L. Jaffe, T. Halicioglu and P. Koumoutsakos,On the Water-Carbon Interaction for Use in Molecular Dynamics Simulations of Graphite and Carbon Nanotube, J. Phys. Chem. B107, 1345–1352 (2003)

2003
[24]

W loch, A

J. W loch, A. Terzyk and P. Kowalczyk,New forcefield for water nanodroplet on a graphene surface, Chem. Phys. Lett.,674, 98–102 (2017)

2017
[25]

Giovambattista, P

N. Giovambattista, P. G. Debenedetti and P. J. Rossky Effect of Surface Polarity on Water Contact Angle and Interfacial Hydration Structure, J. Phys. Chem. B111, 9581–9587 (2007)

2007

[1] [1]

Young,An Essay on the Cohesion of Fluids, Philos

T. Young,An Essay on the Cohesion of Fluids, Philos. Trans. R. Soc. Lond.95, 65–87 (1805)

[2] [2]

Dupr´ e,Th´ eorie m´ ecanique de la chaleur, Gauthier- Villars (1869)

A. Dupr´ e,Th´ eorie m´ ecanique de la chaleur, Gauthier- Villars (1869)

[3] [3]

D. Bonn, J. Eggers, J. Indekeu, J. Meunier, and E. Rol- ley,Wetting and spreading, Rev. Mod. Phys.81, 739–805 (2009)

2009

[4] [4]

J. N. Israelachvili,Intermolecular and Surface Forces, 3rd ed. (Academic Press, London, 2011)

2011

[5] [5]

de Gennes,Wetting: statics and dynamics, Rev

P.-G. de Gennes,Wetting: statics and dynamics, Rev. Mod. Phys.57, 827–863 (1985)

1985

[6] [6]

Li et al.,Effect of airborne contaminants on the wet- tability of supported graphene and graphite,Nat

Z. Li et al.,Effect of airborne contaminants on the wet- tability of supported graphene and graphite,Nat. Mater., 12, 925–931 (2013)

2013

[7] [7]

Giacomello, L

A. Giacomello, L. Schimmele, and S. Dietrich,Wetting hysteresis induced by nanodefects, Proc. Natl. Acad. Sci. U.S.A.113, E262–E271 (2016)

2016

[8] [8]

Y. Si, C. Yu, Z. Dong, and L. Jiang,Wetting and spread- ing: Fundamental theories to cutting-edge applications, Curr. Opin. Colloid Interface Sci.36, 10–19 (2018)

2018

[9] [9]

Chandler,Interfaces and the driving force of hy- drophobic assembly, Nature437, 640–647 (2005)

D. Chandler,Interfaces and the driving force of hy- drophobic assembly, Nature437, 640–647 (2005)

2005

[10] [10]

Giovambattista, P

N. Giovambattista, P. J. Rossky, and P. G. Debenedetti, Computational studies of pressure, temperature, and sur- face effects on the structure and thermodynamics of con- fined water, Annu. Rev. Phys. Chem.63, 179–200 (2012)

2012

[11] [11]

N. B. Rego and A. J. Patel,Understanding hydrophobic effects: Insights from water density fluctuations, Annu. Rev. Condens. Matter Phys.13, 303–324 (2022)

2022

[12] [12]

K. Lum, D. Chandler, and J. D. Weeks,Hydrophobicity at small and large length scales, J. Phys. Chem. B103, 4570–4577 (1999). 6

1999

[13] [13]

K. A. Dill, S. B. Ozkan, M. S. Shell, and T. R. Weikl,The protein-folding problem, Annu. Rev. Biophys.37, 289– 316 (2008)

2008

[14] [14]

Luzar and D

A. Luzar and D. Chandler,Hydrogen-bond kinetics in liq- uid water, Nature379, 55–57 (1996)

1996

[15] [15]

F. H. Stillinger,Water revisited, Science209, 451–457 (1980)

1980

[16] [16]

N. A. Loubet, A. R. Verde and G. A. Appignanesi,A water structure indicator suitable for generic contexts: Two-liquid behavior at hydration and nanoconfinement conditions and a molecular approach to hydrophobicity and wetting, J. Chem. Phys.160, 144502 (2024)

2024

[17] [17]

N. A. Loubet, A. R. Verde and G. A. Appignanesi,The nature of water interactions and the molecular signatures of hydrophobicity, J. Chem. Phys.162, 244703 (2025)

2025

[18] [18]

J. M. Montes de Oca, F. Sciortino and G. A. Appignanesi, A structural indicator for water built upon potential en- ergy considerations, J. Chem. Phys.152, 244503 (2020)

2020

[19] [19]

A. J. Patel, P. V´ arilly, and D. Chandler,Fluctuations of water near extended hydrophobic and hydrophilic sur- faces, J. Phys. Chem. B114, 1632–1637 (2010)

2010

[20] [20]

Tinti, A

A. Tinti, A. Giacomello, Y. Grosu, and C. M. Cas- ciola,Intrusion and extrusion of water in hydrophobic nanopores, Proc. Natl. Acad. Sci. U.S.A.114, E10266– E10273 (2017)

2017

[21] [21]

Godawat, S

R. Godawat, S. N. Jamadagni, and S. Garde,Character- izing hydrophobicity of interfaces by using cavity forma- tion, solute binding, and water correlations, Proc. Natl. Acad. Sci. U. S. A.106, 15119–15124 (2009)

2009

[22] [22]

G. B. Sigal, M. Mrksich, and G. M. Whitesides,Effect of surface wettability on the adsorption of proteins and detergents, J. Am. Chem. Soc.120, 3464–3473 (1998)

1998

[23] [23]

Werder, J

T. Werder, J. H. Walther, R. L. Jaffe, T. Halicioglu and P. Koumoutsakos,On the Water-Carbon Interaction for Use in Molecular Dynamics Simulations of Graphite and Carbon Nanotube, J. Phys. Chem. B107, 1345–1352 (2003)

2003

[24] [24]

W loch, A

J. W loch, A. Terzyk and P. Kowalczyk,New forcefield for water nanodroplet on a graphene surface, Chem. Phys. Lett.,674, 98–102 (2017)

2017

[25] [25]

Giovambattista, P

N. Giovambattista, P. G. Debenedetti and P. J. Rossky Effect of Surface Polarity on Water Contact Angle and Interfacial Hydration Structure, J. Phys. Chem. B111, 9581–9587 (2007)

2007