The phenomena occurring in solution and bulk polymerizations conducted at high temperatures (>~200 °C) are quite different from those known at moderate temperatures. Backbiting and scission reactions dominate, and termination reactions have less impact on the shaping of the molecular weight distribution and the polymer properties. Polymer products made at these temperatures generally show a low molecular weight multimodal distribution dominated by the presence of various oligomeric products resulting from chain scission. These features result in unique products suitable for use in specialized applications in coatings, inks, and waterborne paints. Campbell Morbidelli and I have conducted a complete theoretical and experimental investigation of the high temperature polymerization of Styrene and provided the first complete understanding of the conduct of these processes, both in homopolymerization, and in crosslinking copolymerization. Interestingly, the introduction of crosslinking at such high temperatures does not lead to gelation because of the counter-effect of chain scission. We studied the dynamic progression of this process and managed to develop a patented process for making hyperbranched polymers. Those are of prime importance for use as rheology modifiers, or controlled release agents.

• Campbell, J. D., F. Teymour, and M. Morbidelli. "High Temperature Free Radical Polymerization. 1. Investigation of Continuous Styrene Polymerization." Macromolecules 36(15), pp.5491-5501, 2003.

• Campbell, J. D., F. Teymour, and M. Morbidelli. "High Temperature Free Radical Polymerization. 2. Modeling Continuous Styrene Polymerization." Macromolecules 36(15), pp.5502-5515, 2003.

• Campbell, J. D., F. Teymour, and M. Morbidelli. "Production of Hyperbranched Polystyrene by High-Temperature Polymerization." Macromolecules 38(3), pp.752-760, 2005.

• “Process for producing hyperbranched polymers”, J. David Campbell and Fouad Teymour, U.S. Patent 5,986,020. November 16, 1999.