Chem. Rev. 1988, 88, 927-941 927 Interfacial Lifshitz-van der Waals and Polar Interactions in Macroscopic Systems CAREL J. VAN OSS’ Departments of Microbloiogy and Chemical Engineering, State University of New York at Buffalo, Buffalo, New York 14214 MANOJ K. CHAUDHURY Do w Corning Corporation, Midland, Michigan 48686 ROBERT J. GOOD Department of Chemical Engineering, State University of New York at Buffalo, Buffalo, New York 14260 Received November 2, 1987 (Revised Manuscript Received July 8, 1988) Contents C. Direct Measurement of Interfacial 939 Interaction Forces I. Introduction 927 1. Attractive Forces between Apolar 939 11. Theory 929 Surfaces Immersed In Water A. Lifshitz-van der Waals (LW) Interactions in 929 2. Interactions between Weakly Polar 939 the Condensed State Surfaces Immersed in Water 1. Lifshitz Approach 929 3. Repulsion Forces between Strongly 940 2. Interfacial LW Interactions 930 Polar Surfaces Immersed in Water 3. Attractive and Repulsive LW 93 1 IV. References and Notes 940 Interactions 4. Young’s Equation 93 1 I. Introduction 5. Decay with Distance of LW Interactions 93 1 6. Polar or Electron Acceptor-Electron Donor 932 The concept of a general attractive interaction be- Interactions tween neutral atoms was first proposed by van der 1. Surface Thermodynamics of (Lewis) 932 Waals in 1873, to account for certain properties of Acid-Base (AB) Interactions nonideal gases and liquids.’ Three different but nev- 2. The Young-Dupr6 Equation 933 ertheless related phenomena were subsequently shown to contribute to these “van der Waals” interactions: (1) 3. Positive and Negative Interfacial 933 randomly orienting dipole-dipole (or orientation) in- Tensions teractions, described by Keesom;2-6 (2) randomly or- 4. Monopolar Surfaces 934 ienting dipole-induced dipole (or induction) interac- 5. Decay with Distance of AB Interactions 935 tions, described by Debye;6?7(3) fluctuating dipole-in- C. Electrostatic Interactions 935 duced dipole (or dispersion) interactions, described by 1. The Electrokinetic Potential 935 London.8 Of these three, Keesom and Debye interac- tions are found with molecules that have permanent 2. Free Energy and Decay with Distance 935 of Electrostatic Interactions dipole movements. The London interaction is universal and is present in atom-atom interactions as well. All D. Energy Balance 936 three interaction energies between atoms or small II I. Experimental Approaches and Verification 937 molecules decay very steeply with distance (d), as d4. A. Contact Angle Determination of LW and 937 For various reasons, only van der Waals-London (dis- AB Interactions persion) interactions have been held to be of prepon- 1. Young’s Equation and Its Utilization 937 derant importance between macroscopic bodies in 2. Interfacial Tensions between Liquids 937 condensed systems?JO Hamaker developed the theory of van der Waals-London interactions between ma- 3. Interfacial Interactions between 937 croscopic bodies in 1937 and showed that the additivity Different or Similar Materials Immersed of these interactions renders them considerably more in Liquids long-range; i.e., the dispersion energy between two 4. Relation between the LW Surface 937 semiinfinite parallel flat slabs decays with distance as Tension and the LW Constant A d-2 l1 for relatively short distances (d < 100 A) and, due 5. Implications of AB Interactions 938 to retardation, as d-3 at greater distance^.^^'^ B. Electrokinetic Measurements and EL 939 The realization of the existence of these relatively Interactions long-range attractive forces made possible the first 0009-2665/88/0788-0927$06.50/0 0 1988 American Chemical Society 828 Chemical Reviews, 1988. VoI. 88. No. 6 van Oss et al. ...r , , Carel J. van Oss studied in The Netherlands and France (Ph.D. 1955, Sorbonne, Paris; Physical Biochemistry). After postdoctoral studies In The Netherlands (van't Hoff Laboratory of Physical and Colloid Chemistry, University of Utrecht) and in France (Electro- Robert J. Good received his B.A. in Chemistry from Amherst chemistry Laboratory, Sorbonne, Paris) he was Director of the College in 1942, his M.S. from the University of California, and his Laboratory of Physical Biochemistry in the National Veterinary m.D. from the University of Michigan. He has been employed by College of Alfort (Paris) (1958-1963). In 1963 Dr. van Oss be- Monsanto. Dow. American Cyanamid. and General Dynamics. He came Assistant Director of the Department of Microbiology at taught from 1956 to 1959 at the University of Cincinnati, and since Montefiore Hospital and Medical Center, New York. NY. From 1964 he has been Professor of Materials Science at the State 1965 to 1968 he was Director of the Serum, Plasma, and Immu- University of New York at Buffalo. He has held visiting positions nochemistry Departments of the Milwaukee Blood Center and at tJ?e NIH. at Um University of Bristol. at Imperial College, London. Adjunct Associate Professor of Biology at Marquene University, end at the City University, London; he was Visiting Scholar at the Milwaukee. WI. In 1968 Dr. van Oss joined the Department of Kendall Corp., Lexington, MA. in 1987. In 1957, with one of his Microbiology, SUNY at Buffalo. He currently is Professor of Mi- first students (Louis A. Girifalco) and with Dr. Gerhard Kraus, he crobiology and Adjunct Professor of Chemical Engineering at the proposed Um "geometric mean" relation for Um energy of adhesion State University of New York at Buffalo. He is Head of the Lab- between two phases across an interface and the energies of co- oratory of Immunochemistry of Um Depatiment of Microbiology and hesion of the separate phase. His recent interests include hydro- a member of the Emest Witebsky Center for Immunology at SUNY gen bonding across interfaces. contact angles of liquids on solids, at Buffalo. He has held visiting positions at the Central Laboratory surface "odynamics, microemulsbns. the role of viscoelasticity of the Netherlands Red Cross Blood Transfusion Service at Am- and elongational viscosity in practical adhesion. and the theory of sterdam. and at the University of Bristol. Dr. van Oss is Editor- passivity. He received the Kendall Award of the ACS in 1976 and in-Chief of the journals Preparative Biochemistiy. Immunological the Schoellkopf Award of the Western New York Section of the Invest@tbns, and Separation and Purificatbn Memods and SWNWS ACS in 1979. He is the author or coauthcn of 120 papers and one on the editorial boards of various other journals. He is the author patent and is coeditor of three books. of 235 papers and numerous abstracts and coauthor or coeditor of five books; he holds eight patents. His current research invoives studies of polar and apolar interactions in macroscopic systems, and Derjaguin and LandauIg and, independently, by cell separation methods. the nature of the interaction between Verwey and Overbeek.2°-z1 The general theory of col- antigens and antibodies. and physicochemical and immunochemical cell surface characterization. loidal stability, based on these considerations, has be- come known as the DLVO theory, by combining the initials of these four authors.1kz1 Hamaker already indicated in 1937 that it was pos- sible for the van der Waals-London interaction between two different materials immersed in a liquid to be re- pulsive." This was reaffirmed by Derjaguin in 1954,n and Visser subsequently established the precise con- ditions necessary for the occurrence of repulsive van der Waals-London for~es.2~*~~Fowkes was the first to in- dicate a few possible examples of such repulsions," and van Oss et al. demonstrated the existence of many such systems, leading to phase separationsz6 as well as to particle exclusion.z' It had, however, long been surmised that physical forces other than van der Waals attraction and elec- trostatic repulsions could also play a role in colloidal Menoj K. Chaudhuty graduated with a Ph.D. in Chemical Engi- interactions. An important force among these is often nearing from the State University of New York at Buffalo in 1984. alluded to as 'hydrophobic interaction",28 an effect that He carrled out his doctoral research under Professor R. J. Good has resisted quantitative experimental determination on topics related to wntact angle and wettabilii. Currently he is well as precise theoretical definition until relatively employed at Dow Corning Corp., Silicone Research Division. His as research interests are in surface chemistry and adhesion. Dr. re~ently;~.~~see also section IIIC. Closely linked to Chaudhury is the recipient of the V. K. LaMer Award in Surface hydrophobic interaction, which is generally so called Chemistry and the H. Down Industrial Scientist Award. when attractive, is "hydration which is ita repulsive It now transpires that these theories of the stability of hydrophobic colloids, as a interactions, which are of polar (but not electrostatic) balance between van der Waals attraction and electrical origin, either in the attractive (hydrophobic interaction) double-layer repulsion, by Hamaker13and de Boer.14 or in the repulsive mode (hydration pressure) represent These theories were further elaborated by De~jaguin'~~'~ energies that may be up to two decimal orders of Interfacial Interactions in Macroscopic Systems Chemical Reviews, 1988, Vol. 88, No. 0 029 magnitude higher than those commonly encountered 2 separated by a film of phase 3 of thickness 1 is among the components of traditional DLVO energy balances.29*30~32~33These polar interactions are largely based on electron acceptor-electron