Polymerizations induced by ionizing radiation

New Views on Cationic Polymerizations Induced by Ionizing Radiations (1993)... 

The equilibrium between ions and ion pairs is not maintained in all polymerizing systems. For example, the cationic polymerization induced by ionizing radiation produces the positive and negative ions, the latter initiating a free carbonium ion propagation which is terminated by their collision with negative ions. Such a collision destroys the free ions, and hence their stationary, but not the equilibrium, concentration is determined by their rate of formation and destruction. 

Prof. Szwarc also contributed to the understanding of mechanisms of cationic polymerizations. In addition to the previously mentioned study of the cationic polymerization of styrene initiated by trifluoroacetic acid, he developed novel methods of initiation of cationic polymerization, e.g., the initiation of cationic polymerization by transfer of Cl " and N02 ions, and initiation by electron-transfer. In cooperation with deSorgo and David Pepper, he carried out the first stop-flow study of cationic polymerization that demonstrated the formation of the positive polystyryl cation and allowed its spectrum to be recorded. This work was published in J.C.S. Chem. Comm. 419, (1973). He was the first to point out that cationic polymerization induced by ionizing radiation is propagated by free cations [Makromol. Chem. 35a. 123 (I960)]. 

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