THE TRIBOLOGY TRUST
(Administered by the Institution of Mechanical Engineers)
The 2012 Tribology Gold Medal Awarded to:
PROFESSOR JACOB KLEIN
In recognition of his outstanding contribution to tribology in particular molecular brush lubrication and hydration lubrication
Professor Jacob Klein was born in Tel-Aviv, Israel in 1949 He obtained a 1st Class Honours degree in Physics (1973) from Cambridge University and in 1974-77 he researched in the University’s Cavendish Laboratory under the supervision of Professor David Tabor, the first recipient of the Tribology Gold Medal (1972), receiving his MA and PhD in 1977.
In 1977 he joined the Weizmann Institute of Science in Israel. He was appointed Professor in 1987, headed its Polymer Research Department in 1989-91, and chaired its Scientific Council during 1999-2000. Concomitantly, in 1980-1984 he was a University Demonstrator in Physics and Fellow of St. Catharine’s College, at the University of Cambridge.
In 2000 he was appointed the Dr. Lee’s Professor of Chemistry and Head of Department of Physical and Theoretical Chemistry at the University of Oxford, and in 2007 returned full-time to the Weizmann Institute, where he is the Herman Mark Professor of Polymer Physics.
Prof Klein has held visiting professorships in several universities including the University of California at Santa Barbara, the Ecole Polytechnique in Lausanne, the Ecole Superieure de Physique et Chemie in Paris, Princeton and Cornell Universities and the State Key Laboratory for Tribology, Tsinghua University, Beijing.
Professor Klein’s main achievements cover several areas related to tribology. Amongst these the most outstanding achievements are in the area of friction and boundary lubrication by polymers at surfaces and by highly-confined liquids, especially his pioneering discovery of hydration lubrication, and of its origins and application possibilities. This work was based on Professor Klein’s experimental studies using uniquely-sensitive, self-designed devices (Surface Force Balances) for force and friction measurements at the molecular level.
He explored, in impressive style, basic properties of systems on a molecular scale, including the friction and lubrication of polymers. In particular, he developed the remarkable experiments to investigate, at a molecular level, the friction associated with brush-like polymer boundary layers, indeed he has been a prime mover in developing the powerful concept of molecular brush lubrication. This mechanism has attracted much interest in various laboratories around the world, the main achievements being the discovery of how boundary lubrication operates at the solvated polymer-polymer interface.
Professor Klein’s recognition of the role of configurational entropy in controlling friction between polymer brushes has been very influential. In addition, the whole area of lubrication in aqueous media has been transformed by Prof Klein’s findings on hydration lubrication. His researches reveal that hydration layers of highly dipolar water molecules surrounding charges, whether on ions, on charged polymer brushes, or using classical boundary lubricants of polar surfactants, can dramatically reduce friction between sliding surfaces under water.
He and his students have developed elegant friction test machines (based on the surface force apparatus), which enable tribologists to see optically the sliding of surfaces across nanometrically-thin films of liquids and polymers at a molecular interface, over a large range of sliding speeds from nm/s to mm/s. At the same time, angstrom-level sensors capture the friction behaviour with unique sensitivity and resolution.
Professor Klein has been consultant to world acknowledged companies, including Proctor & Gamble, Kodak, Unilever and Exxon. However, with his increasing standing in the scientific world, Professor Klein exerted considerable influence on education, directing students at Cambridge University, the Weizmann Institute and at Oxford University. Furthermore, because of his studies, tribology research – at the molecular scale – is now performed throughout the world in some of the best physics, chemistry and material science laboratories.
In summary, Prof Klein’s contributions over the years to tribology of soft matter and of aqueous systems, particularly his work on lubrication by polymer brushes and his recent discovery and development of the concept of hydration lubrication, have transformed our understanding of these areas. In addition they have great potential for applications in biological and biomedical systems.
His awards and honours are numerous. To these is now added the world’s highest award in tribology – the Tribology Gold Medal, of which Professor Klein is indeed a most worthy recipient.