Radical Polymerization – Kinetics and Mechanism

Radical Polymerization – Kinetics and Mechanism

by Philipp Vana

4th International Symposium on Radical Polymerization—Kinetics and Mechanism

Participants in the 4th Symposium on Radical Polymerization—Kinetics and Polymerizations

The conference was attended by more than 180 scientists from 23 countries, including around 25 persons from chemical industry and more than 25 scientists from non-academic research institutions. It is especially noteworthy that quite a substantial number of Ph.D. students, mostly from European countries, attended the conference and actively participated. The well-proven format of the symposium series was maintained in that the entire area of radical polymerization was covered. Clustering around the central theme of kinetics and mechanisms of radical polymerization, the lectures were organized in five sections:

• Fundamentals

• Polymer Characterization

• Controlled Radical Polymerization

• Polymer Reaction Engineering, including Simulations

• Heterogeneous Polymerization

As with the previous meetings, there were no parallel sessions. This organizational mode is a very popular feature of this conference series, and the fact that every attendee has the same information available stimulates the scientific discussion after the talks. In addition to the 25 invited lectures, 8 papers were selected from the submitted posters for oral presentation. The lecture program was complemented by 116 posters, which were mounted inside the lecture hall over the entire week. Four poster sessions of two hours each gave plenty of time for extensively discussing all contributions, demonstrating the fact that within the course of this meeting posters were considered equally important as lectures. Three outstanding poster contributions were selected by the conference participants to receive poster awards.

• The prestigious SML poster prize (SML is for Santa Margherita Ligure, where the first meeting in this series was organized in May 1987) was awarded to J. Reuber and D. Johannsmann for “Formation of Thermo-Responsive Hydrogel Films via Electrochemically Initiatied Polymerization.”

• C. Yoshikawa, A. Goto, Y. Tsuji, and T. Fukuda received an IUPAC poster prize for “Protein Repellency of Concentrated Polymer Brushes Prepared by Surface-Initiated Living Radical Concentration.”

• P.J. Saikia and S. Choe received an IUPAC poster prize for “The Influence of Reversible Addition Fragmentation Chain Transfer Agent on the Dispersion Polymerization of Styrene.”

Yoshikawa and Saikia each received a certificate signed by the IUPAC president, a copy of the IUPAC Gold Book, and a two-year subscription to Chemistry International.

It is difficult to present selected contributions from the multitude of excellent talks and posters without disregarding other important papers. A complete compilation of oral contributions as well as selected poster presentations have been published in Macromolecular Symposia volume 248, February 2007 (see page 26). In summary, some important developments in the field of radical polymerization kinetics became evident through the presented research:

• Knowledge of the basic kinetics and mechanisms of radical polymerization has increased tremendously in recent years due to the application and further development of powerful experimental techniques such as the pulsed laser polymerization methods.

• The use of controlled radical polymerization (CRP) for obtaining well-defined macromolecules is rapidly growing. Novel methods, which pursue new concepts and employ new types of mediating agents, are emerging, and the already established methods, such as NMP, ATRP, and RAFT, are continuously refined and explored in depth. The kinetics and mechanism of the various CRP methods are subject of intense research and the concepts of CRP are sparking the development of new techniques for studying fundamental aspects of radical polymerization.

• Many researchers are using their kinetic expertise for rationally designing new polymerization processes (e.g., polymerization from surfaces or generation of colloidal particles) for designing novel polymeric materials.

• Radical polymerization in aqueous phase is becoming increasingly important. Aside from progress understanding emulsion polymerization, an increasing body of work is addressing radical polymerization of strongly polar and ionic monomers in homogenous aqueous phase.

These tendencies underpin the fact that radical polymerization is progressively expanding into new areas. Recent advances in the field, which were mainly driven by the rapid development of controlled radical polymerization, now offer the opportunity of introducing high degrees of control by radical polymerization over physical and chemical properties. Molecular weight, polydispersity, intramolecular chemical composition distribution, glass transition temperature, branching and branching distribution, the incorporation of functional groups, particle morphology in heterogeneous systems, and polymer surface properties can now be tailored with unrivalled precision under retention of the versatility and robustness of radical polymerization. The improved control over the resultant macromolecular properties will lead to more efficient polymer production and new polymer products.

Philipp Vana <pvana@uni-goettingen.de> teaches at the University of Göttingen, Germany, and is chairman of an IUPAC task group on RAFT polymerization. He was a member of the scientific secretariat of the SML06 meeting.