ABSTRACT
ROBERT H. DETTRE Du Pont Chemicals, E. I. du Pont de Nemours & Co., Inc., Wilmington, Delaware
I. Introduction 2
II. Commentary on the Thermodynamics of Wetting 4 A. Ideal wetting model 4 B. Solid surface and interfacial tensions 5 C. Young and modified Young equations 6 D. Works of adhesion and cohesion 7 E. Adhesion tension 9 F. Spreading coefficients 9 G. When the contact angle approaches zero 10
III. Contact-Angle Hysteresis and Experimental Procedures 11 A. Experimental 11 B. Hysteresis 14
IV. Wetting of Low-Energy Surfaces 25 A. Historical perspective 25 B. Molecular models and dispersion theory 30 C. Model of Hough and White 33 D. Model of Israelachvili 34 E. Applications of dispersion force theory 37
V. Surface Structure 44 A. Surface solubility 44
B. Monolayers and polymers 45 C. Summary: Wetting of low-energy surfaces 50 D. Hamaker constants from contact angles 52
VI. Liquids Spreading on Liquids 54
VII. Interfacial Wettability 57 A. Bartell-Osterhof equation 57 B. Interfacial contact-angle hysteresis 60 C. Measurement and data presentation 63
Appendix I. Surface Tension and Surface Stress 68
Appendix II. Gibbs: Another Method and Notation 68
Appendix III. Another Form of the Bartell-Osterhof Equation 70
References 71
I. INTRODUCTION Wetting involves the interaction of a liquid with a solid. It can be the spreading of a liquid over a surface, the penetration of a liquid into a porous medium, or the displacement of one liquid by another. It can help to characterize surfaces and to determine solid/liquid interactions.
