Marco Steenbock

Triazolinyl Radicals - New Additives for Controlled Radical Polymerization

The effect of the addition of the triazoline derivative 1 on the radical polymerization of styrene and some methacrylates is discussed. The polymerization of styrene in the presence of 1 exhibits the characteristics of a controlled radical polymerization such as a linear time-conversion development and increasing molecular weights versus conversion. Additionally, even monomers other than styrene, namely methacrylates, can be polymerized in a controlled fashion. Furthermore, the properties of the isolated PS and PMMA samples were studied. It will be shown, that polymers obtained by controlled radical polymerization in the presence of 1 possess triazolinyl end-groups and the degree of end-functionalisation will be estimated. To demonstrate the ability of the polymers to reinitiate, chain extension experiments were performed on our PS-samples.

Self-regulation of controlled radical polymerization

The number of stable free radicals in solution usually increases in a controlled radical polymerization due to irreversible side reactions of free polymer-radicals. In our approach, this increase is, depending on the amount of side reactions, prevented by slow decomposition of the counter radical and by simultaneous formation of new initiating species. While the controlled radical polymerization in the presence of completely stable radicals is generally possible only (at least without great difficulty) for monomers with the tendency to spontaneous initiation (e.g. thermal initiation of styrene), our system is self-regulating and therefore independent of initiating properties of the monomer. The concept was proven by controlled radical polymerization of methacrylates and styrene in the presence of two triazolinyl radicals 1 and 2 with different thermal stabilities.