Energy, controlled radical polymerization

Matyjaszewski K, McCullough L, Yoon JA, Kowalewski T, Park H-J. Nanostructured materials for potential energy-related applications by controlled radical polymerization. In Abstracts of Papers, 240th ACS National Meeting 2010 Boston, MA. 

SYNTHESIS OF FLUOROPOLYMERS USING BORANE-MEDIATED CONTROL RADICAL POLYMERIZATION FOR ENERGY STORAGE APPLICATIONS... 

Durairaj Baskaran performed doctoral studies at the National Chemical Laboratory, India, and University of Mainz Germany, working jointly with Dr. S. Sivaram and Prof. Axel H. E. Muller. After his PhD (University of Pune, India, 1996), he worked as a senior scientist at the National Chemical Laboratory for several years before joining the University of Tetmessee. His research interests are in the areas of living anionic polymerization and controlled radical polymerization focusing on synthesis and characterization of architecturally controlled polymers, functionalization of carbon nanotubes, nanocomposites, and polymers for energy applications. He has published over 70 research articles and several patents and also coedit i a book. 

As is expected from these results, it is very difficult to control the polymerization of monomers other than St, e.g., that of MMA, because of the too small dissociation energy of the chain end of poly(MMA). In fact, the polymerization of MMA in the presence of TEMPO yielded the polymer with constant Mn irrespective of conversion, and the Mw/Mn values are similar to those of conventional polymerizations [216]. The disproportionation of the propagating radical and TEMPO would also make the living radical polymerization of MMA difficult. In contrast, the controlled polymerization of MA, whose propagating radical is a secondary carbon radical,has recentlybeen reported [217]. Poly(MA) with a narrow molecular weight distribution and block copolymers were obtained. 

Polymerization in bulk, that is, of undiluted monomer, minimizes any contamination of the product. Bulk polymerization is difficult to control, however, due to the high exothermicity and high activation energies of free-radical polymerization and the tendency toward the gel effect in some cases. 

Free-radical polymerizations are highly exothermic. A typical adiabatic temperature rise for bulk (mass) polymerization of 200-500°C may not be uncommon. The overall activation energy for polymerization is in the order of 80 15 kj mol . The dramatic increase in the heat load during the gel-effect period can result in loss of temperature control, non-isothermal reactor operation and potential rimaways. Non-isothermal operation, aside from safety concerns, can also adversely affect product quality. 

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