June 3-9, 2001
Il Ciocco (Lucca), Tuscany, Italy
Editor, M. Buback and A.L. German
Wiley-VCH, 2002, pp. 1-303
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.
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
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
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
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.
the symposium comprised 6 major themes:
of Free-Radical Polymerization (8 lectures);
Polymerization in Supercritical Fluids (3 lectures);
- Polymer Characterization
- Polymer Reaction
Engineering (4 lectures);
Radical Polymerization (9 lectures); and
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
- 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
- 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.
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