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September 2006 |
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| Who's Who in Surface Science (Part 1) | ||||||
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This month our feature topic will focus on people --
notably people who we believe have made a significant impact in the
arena of contact angle and surface science. The following list is
certainly not comprehensive. Surely many dozens or even hundreds of
researchers and scientists have devoted tremendous personal energies to
this science -- and consequently should be noted. This list is in no particular order. Nor is the list
comprehensive. (Most likely we'll do a Part 2 to this article in a
future newsletter.)
1. Thomas Young. Perhaps the original pioneer in contact angle science, Young in 1805 described the interaction between the forces of cohesion and adhesion which in turn determines wettability in his "Philosophical Transactions of the Royal Society of London". For a detailed overview please refer to the article on Surface Energy we contributed to Wikipedia: http://en.wikipedia.org/wiki/Surface_energy. Young also developed the well-regarded Young's Modulus which is used to measure the stiffness of a material as well as Young's Equation which defines the balances of forces caused by a wet drop on a dry surface.
2. Johannes Diderik van der Waals. Dr. van der Waals (1837-1923), like Thomas Young, is another famous classic scientist. He is best known for his work on the equation of the state for gases and liquids which won him a Nobel Prize in Physics in 1910. Today he is better known for his eponymous discoveries, e.g., van der Waals forces, van der Waals interactions, van der Waals bonds. These foundations have been critical to the development of absorption theories including the Work of Adhesion tool used by the ramé-hart DROPimage software. Water molecules in liquid state are attracted to one another by van der Waals forces (or bonds). While the water molecule as a whole is neutral, the distribution is not symmetrical. This results in a dipole moment which is defined as the separation of the positive and negative centers of charge. This phenomenon results in a net attraction between such polar molecules and contributes to the surface tension. Even nonpolar molecules may experience a weak version of van der Waals bonding which, in turn, results in lower surface tension.
3. William A. Zisman. Dr. Zisman has been a pioneer in contact angle science. During the 1950's, 60's, 70's and even until his passing in the 1990's, Dr. Zisman is responsible for bringing mainstream the modern goniometer. While doing research at the Bethesda Naval Research Lab in Maryland (during the 1950's and 60's), Dr. Zisman designed an instrument to measure the contact angle of a drop of liquid on a solid. The lab commissioned a small specialty machine shop in New Jersey by the name of ramé-hart to build the instrument. Thus the first Model 100 Goniometer was born. Since then, ramé-hart has hand built thousands of Model 100 Goniometers based on Dr. Zisman's design, many of which are still in use today. Dr. Zisman developed a method that allows a series of contact angle measurements using the same substrate but different liquids to be plotted. Called Zisman's Plot it determines what is referred to as the Critical Surface Tension -- which may or may not be the same as the surface energy. Zisman's Plot tool is an integral part of our DROPimage application. Dr. Zisman is the coauthor of "Competitive Adsorption from Solution between Hydrophobic and Hydrophilic Molecules and Ions" (1952), the author of "Surface Energetics of Wetting, Spreading, and Adhesion" (1972), and has published many papers and other books. He is the recipient of the Mayo D. Hersey Award (1969), the American Chemical Society Award in Colloid and Surface Chemistry (1963) and in Applied Polymer Science (1977), and numerous other awards and recognition. At his retirement gala Rolf Pfiel of ramé-hart presented Dr. Zisman with a miniature Model 100 Goniometer. 4. Carel Jan van Oss. van Oss is a native of the Netherlands where he is a decorated war hero. During WWII he assisted many hundreds of Jews from Nazi invaders by forging documents. He came to the US in 1963 and in 1967 became a professor at the University of Buffalo. Dr. van Oss is currently Professor Emeritus of Microbiology. Earlier this year he presented a paper entitled "Properties of Water in Colloidal and Biological Systems" at the Fifth Contact Angle Symposium in Toronto. In his presentation, he referred to "hyper-hydrophobicity" which describes the interface between water and air, particularly with regard to a cluster formation of water molecules and the "extraordinary variability" of the ratio of the electron-accepticity and the electron-donicity of the water as a function of temperature. Further, he described how this phenomenon will affect all polar interactions that occur in the water. Dr. van Oss has published over 300 papers and (11) books -- including "Colloid & Surface Properties of Clays and Related Minerals" (2002). He has made a number of significant contributions to surface science. Most notable perhaps is his contribution to the measurement of surface energy using what is commonly referred to as the Acid-Base Tool. This tool evaluates the surface energy of any solid by using the contact angle measurements of three different test liquids. Dr. van Oss and others (including Dr. Chaudhury, see below) have shown that the acid-base interactions can be described by the electron donor and accepter components of the test liquids -- of which one is apolar an the other two are polar. Our DROPimage Standard and DROPimage Advanced software incorporates the Acid-Base Tool based on this the work.
5. Daniel Y. Kwok. Dr. Kwok has published dozens of papers on contact angle and surface energy. His work includes extensive study of the Axisymmetric Drop Shape Analysis (ADSA) method which is employed by our DROPimage Advanced software. Additionally, he developed a formula used by our new "One Liquid Surface Energy Tool" which describes the correlation between the contact angle, the surface tension of the liquid and the surface energy of the solid. Dr. Kwok has done work at MIT as well as the University of Toronto. 6. Frederick M. Fowkes. The late Professor Fowkes (b. 1915) is credited for his work at Lehigh University in the area of interfacial tension and surface energy. He is widely known for his work based on Lewis acid-base interactions -- including the two-liquid surface energy tool which is used today in our DROPimage software. He is the recipient of numerous awards including: the Award for Excellence in Adhesion Science from the Adhesion Society (1989). He is also the author of dozens of papers and articles which spanned his career. 7. Kash Mittal. Dr. Mittal is an illustrious and colorful authority on contact angle and surface science. He is currently co-director of MST Conferences (along with Dr. Robert Lacombe) which has been organizing the Contact Angle Symposium since 1990 having recently finished their fifth version. Dr. Mittal is a prolific writer and editor. I can think of no one that has edited more books on surface science than Dr. Mittal. He is the editor of the Journal of Adhesion Science and Technology and has been the editor for over 75 books on contact angle, adhesion, interface science, surface cleaning, particle adhesion and removal, surfactants, and high temperature polymers. He can be reached at http://www.mstconf.com/.
8. Manoj Chaudhury. Professor Chaudhury is the recipient of the 2005 Award for Excellence in Adhesion Science from the Adhesion Society for his efforts in describing surface thermodynamics and wettability. He is known for his work on surface energetics of silicone elastomers, surfaces with gradient surface tension, and expanding on van der Waals interactions through contact angle measurements using polar and apolar liquids. Dr. Chaudhury is editor of the book "Adhesion Science and Engineering" (2002). He has also published over six dozen papers in scientific journals, a number of book chapters, and has contributed work on various patents relating to bonding silicone elastomers. Dr. Chaudhury has also contributed to the development of the Acid-Base Tool used in ramé-hart DROPimage software. See van Oss above for more details.
If you would like to submit any corrections or comments -- or if you would like to suggest a name for our next Who's Who (probably we'll do a Part 2 in year or so), please contact us.
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