No coin nor oath required. For personal study only.
Professor John Bevington has made an outstanding contribution to polymer chemistry for a period of over 40 years. His pioneering work with radiotracers during that time has resolved a multitude of uncertainties about the mechanisms involved in radical polymerizations. Consequently, a modern understanding of such mechanisms owes much to his efforts.
John graduated from Queens' College, Cambridge in 1943. He stayed in Cambridge to work with Fred Dainton, now Lord Dainton, as a research assistant. The research was government contracted, and because of this there were publication restrictions; nevertheless, it produced John's first research publication, on the oxidation and inflammation of yellow phosphorus . John was subsequently appointed to a Research Fellowship and, during the tenure of this, worked with Professor Norrish on the cross-linking of vinyl polymers by Friedel-Crafts catalysts and also on the polymerization of aldehydes. These were to be his first serious excursions into polymer chemistry and formed the basis of the thesis for a Ph.D., which was awarded in 1949. He has subsequently always maintained an interest in aldehyde polymerization, publishing several reviews on the subject .
In 1948, John was appointed to a lectureship in Chemistry at the University of Birmingham. There, he was very shortly to be joined by the polymer group which moved with Professor (now Sir Harry) Melville from Aberdeen. Thus developed a flourishing group of polymer chemists of international repute led by Harry Melville and whose numbers, in addition to John himself, included Ivor Bengough, George Burnett, Frank Peaker, Norman Grassie and Leslie Valentine.
It was in Birmingham that John foresaw the tremendous potential of radiotracers for studying polymerization processes. If one was to study initiation processes in detail, it was necessary to develop a method of sufficient sensitivity to determine the level of incorporation of initiator fragments in polymers. Radiotracers provided such sensitivity, although their measurement in those days using Geiger counters was not often very efficient. John perfected the counting of 14C products by combusting them to ~4CO2 and then counting them within a gas Geiger counter. He thus achieved almost 100% efficiency in counting and had a method which could be controlled to give both very great sensitivity and acceptable accuracy . Such counting techniques, compared with the more recent scintillation counting methods, were laborious; but they were no less sensitive or accurate than the methods which have largely superseded them. Moreover, they had the considerable advantage in those days of being relatively inexpensive.
After John had developed the counting technique, there followed a very fruitful period in his career. There was scarcely an aspect of radical polymerization which did not benefit from his application of radiotracer techniques and his contributions to the subject played a major role in the success of polymer research at Birmingham in the 1950s and early 1960s. His outstanding achievements were recognized in the award of a D.Sc. by the University of Birmingham in 1957.
John's first application of radiotracers was to initiators. He established a direct means of monitoring rates and efficiencies of initiation, provided that initiator fragments are not incorporated in the polymer by subsequent steps . Moreover, in combination with conventional molecular weight methods, he used labelled end-groups to determine the proportions of the two types of termination in radical homopolymerizations and copolymerizations .
The decomposition of initiators also came under John's scrutiny. By using labelled dibenzoyl peroxide, he demonstrated that yields of carbon dioxide could be used to study the reactivity of various compounds towards the primary benzoyloxy radical . By suitable choice of the position of the label, he determined which of the two possible initiating species, the benzoyloxy or the phenyl radical, was responsible for initiation . This led to an extensive study of this type of competition, using a range of monomers with different peroxide initiators. The concept of competition between reacting species for reference radicals, which was to be the basis for much of John's work over the next few years, was also extended to studies of copolymerizations .
The other aspects of radical polymerization benefitting from John's application of radiotracer techniques during his years in Birmingham are too many to enumerate, in full, in this appreciation. But his use of radiolabelling in studying transfer to polymer [8], transfer to initiator [9], transfer to solvent [10] and inhibition [l 1] were each important contributions. Where labelling with tritium was an advantage, he was not deterred by the immense difficulties, before the successful development of scintillation counting, of detecting this particular radionuclide; he extended the gas Geiger counting technique for this purpose by converting tritiated samples to acetylene .
During his years in Birmingham, John acquired a reputation for outstanding clarity in the presentation of lectures, whether to undergraduate audiences or to international gatherings of polymer chemists. This same gift for clarity was soon to manifest itself in the written word with the publication of his book Radical Polymerization [l 3]. That this work, although published almost 30 years ago, is still regarded as a standard text for many aspects of radical polymerization is a great tribute to John's mastery in perceiving the key areas of a subject. IX
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## Tribute to John Holmes In keeping with a time-honoured tradition, I have been asked to produce an article about John Leonard Holmes on the occasion of his retirement from his position as North American Editor of Organic Mass Spectrometry. I have found this to be difficult task. There is no shor