Reversible Addition-Fragmentation chain Transfer (RAFT) Polymerisation

Johann Zank and John White

We synthesize novel surfactants using Reversible Addition-Fragmentation chain Transfer (RAFT) polymerisation.  The RAFT technique, a more sophisticated variety of conventional free-radical polymerisation, was developed in Australia^[1] and allows the preparation of polymers with low polydispersity, defined microstructure and predetermined molecular weight.  A plethora of reactive transfer (RAFT) agents, such as dithioesters,^{[1, 2]} dithiocarbamates,^{[3, 4]} and trithio-carbonates,^{[3, 5]} have been developed.

One of the main differences compared to other polymerisation techniques is that the reversible deactivation mechanism is a transfer rather than a termination reaction. Conventional initiators can be used and existing polymerisation procedures are not affected by the addition of RAFT reagents. Polymers can be prepared in a batch process using this method, which makes its application extremely interesting from an industrial point of view.

The surfactants prepared by RAFT have been applied successfully in the preparation of high internal phase emulsions.  The stability and structure of these emulsions is currently under investigation.

[1]        T. P. Le, G. Moad, E. Rizzardo, S. H. Thang, WO 98/01478, 1998.

[2]        J. Chiefari, Y. K. Chong, F. Ercole, J. Krstina, J. Jeffery, T. P. T. Le, R. T. A. Mayadunne, G. F. Meijs, C. L. Moad, G. Moad, S. H. Thang, Macromolecules 1998, 31, 5559.

[3]        J. Chiefari, R. T. A. Mayadunne, G. Moad, E. Rizzardo, S. H. Thang, WO 99/31144, 1999.

[4]        R. T. A. Mayadunne, E. Rizzardo, J. Chiefari, Y. K. Chong, G. Moad, S. H. Thang, Macromolecules 1999, 32, 6977.

[5]        R. T. A. Mayadunne, E. Rizzardo, J. Chiefari, J. Krstina, G. Moad, A. Postma, S. H. Thang, Macromolecules 2000, 33, 243.