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Macromol. Symp., Vol. 182, 2002, pp. 1-303

3rd IUPAC-Sponsored
International Symposium on
Free-Radical Polymerization:
Kinetics and Mechanism

Macromolecular Division
June 3-9, 2001
Il Ciocco (Lucca), Tuscany, Italy

Symposium Editor, M. Buback and A.L. German
Wiley-VCH, 2002, pp. 1-303
ISBN 3-527-30472-x

> Contents


Free-radical polymerization, as a science, is now about 80 years old. It began with Hermann Staudinger in the 1920s during the period when he was struggling to convince the world of chemistry that polymers are compounds comprised of molecules with very high molecular weights; he invented the word "Makromolekül" to describe them. By 1927, or thereabouts, his "macromolecular hypothesis" had become accepted by the chemical community. Consequently the notion that radical polymerization was a chain reaction comprising initiation, propagation and termination steps developed during the early 1930s, although termination was not thought to be necessary at first, and was assumed to operate through disproportionation when it did become incorporated into the reaction scheme.

The statistical nature of the reaction was appreciated by G.V. Schulz, who calculated the molecular weight distribution (assuming disproportionation) together with the number- and weight-average molecular weights and their ratio. A few years later, he repeated the calculation for termination by combination. Schulz was also responsible for publishing, in 1936, the first academic kinetic study of the free-radical polymerization of styrene; for academic chemists 'it may be salutary to realize that polystyrene had already been in commercial production for several years at that time.

Although it is invidious to single out certain individuals for mention, even the briefest of reviews cannot fail to refer to such landmark achievements as the 1941 kinetic scheme of Price and Kell, the calculation of the copolymer composition equation by several groups 'in 1944 (N.B. the paper by Dostal in 1936), the copolymerization studies of Mayo and Walling, and the contributions of Bamford, Breitenbach, Melville, Norrish, O'Driscoll and their colleagues during the early development of the subject.

In addition to the straightforward aspects of homogeneous polymerization, systems in which the polymer produced proved to be insoluble in its own monomer, and systems in which the monomer was adsorbed on an added foreign polymer, merited special study. Moreover, the polymerization of dienes was shown not necessarily to result in an insoluble crosslinked network. And a number of other special cases attracted attention prior to the advent of "controlled (or living) radical polymerization".

Reverting to the traditional radical polymerization process, nowadays many polymerization processes of commercial interest are based on the free-radical principle. The free-radical process *is often preferred over other methods of preparation as it is rather robust and less sensitive to trace amounts of impurities.

However, until the late eighties the prevailing opinion was that free-radical polymerization was a mature technique, unable to afford polymers with well-defined structures, and lacking the ability to yield, e.g., narrow molecular weight distributions and block copolymers.

In 1985, a small group of chemists interested in free-radical polymerization discussed the possibility of holding a meeting devoted to radical polymerization, which then showed some signs of reviving after a long fallow period. Two of these chemists, Ken O'Driscoll and Saverio Russo, undertook to organize such a conference (SML-87), and it was duly held in Santa Margherita Ligure (Italy) in May 1987. It was a great success, demonstrating that there was indeed a renaissance in the radical polymerization field, and it catalyzed an even stronger resurgence immediately afterwards.

In May 1996 the second conference (SML-96) of the same title was held, again in Santa Margherita Ligure, and again arranged by Professors O'Driscoll and Russo.

The "IUPAC- Sponsored International Symposium on Free-Radical Polymerization: Kinetics and Mechanism" (SML'OI), held in June 2001, was the third conference in the series on free-radical polymerization, and continued the tradition of holding these meetings in Italy, on this occasion in 11 Ciocco (Tuscany).

SML'O I was attended by 235 scientists from 25 countries all over the world, with a good balance between attendees from industry and academia. It is also noteworthy that quite 'a large number of Ph.D. students, mostly from European countries, attended and actively participated in the scientific program.

During the five-day program totals of 23 invited main lectures, I I contributed papers and 135 posters were presented. Most of the main lectures and some of the short lectures are in this issue of Macromolecular Symposia.

Thematically, the symposium comprised 6 major themes:

  • Fundamentals of Free-Radical Polymerization (8 lectures);
  • Free-Radical Polymerization in Supercritical Fluids (3 lectures);
  • Polymer Characterization (4 lectures);
  • Polymer Reaction Engineering (4 lectures);
  • Controlled Radical Polymerization (9 lectures); and
  • Polymerization in Heterogeneous Systems (5 lectures).

In addition, a special lecture was delivered by Professor Aubrey Jenkins, entitled "The foundations of free-radical polymerization, from Staudinger to Bamford and Schulz".

In looking back, it is a striking fact that not a single paper at SML-87 dealt with "living radicals" (in the current sense of the term), ATRP or RAFT. At the second meeting, SML-96, these topics were addressed in only a small number of papers. But at SML'Ol, they dominated large sections of the program.

Through this series of three conferences, important lines of development become clearly visible:

- Our knowledge of the basic kinetics and mechanisms of free-radical polymerization has tremendously increased over the past years, due to, e.g., the advent of new powerful experimental techniques like pulsed laser polymerization and advanced mass spectrometry;
- The explanations of anomalies' in traditional radical polymerization kinetics have been couched in terms that have tended partially to shift from termination towards propagation;
The overwhelming progress in the area of "Controlled (or Living) Radical Polymerization" (CRP), has created a more definable link between polymerization conditions and polymer (micro) structure; and
Hand in hand with the rapid developments in the chemistry of CRP and in the understanding of its kinetics and mechanisms, increasing attention is being given to, e.g., emulsion systems, which will facilitate the commercialization of CRP.

The above advances now offer the opportunity to introduce high degrees of control over physical and chemical properties through the manipulation of molecular weight, polydispersity, intramolecular chemical composition distribution, glass transition temperature, branching and branching distribution, particle morphology in heterogeneous systems, and the incorporation of functional groups. Improved control over the resultant properties will lead to more efficient polymer production and new polymer products.



The organizers wish to thank the "Foundation Emulsion Polymerization" (SEP) and the "European Graduate School" (EGS) for their financial support.

Parts of this Introduction are taken from the special lecture presented by Professor Aubrey Jenkins.


M. Buback
A.L. German

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