The propagation kinetics of N-vinylcarbazole (NVC) were carefully investigated via the IUPAC-recommended pulsed-laser polymerization/size-exclusion chromatography technique (PLP-SEC) in the temperature range between -20 and 20 °C using 355 nm pulsed irradiation and the photo initiator 2.2-dimethoxy-2-phenylacetophenone (DMPA) as a source of primary radicals. Using this experimental approach, propagation rate coefficients, kp, were not accessible for temperatures exceeding 20 °C. There is strong evidence that the monomer itself is excited by pulsed-laser light of 355 nm, thus contributing to the polymerization process via the formation of free radicals. In addition, UV light-induced cationic polymerization processes can not be ignored as a possible side reaction. NVC polymer also absorbs strongly at 355 nm and we speculate that this may lead to bond scission and branch network formation in the PLP process. Laser-controlled molecular weight distributions are only obtained for reaction temperatures below 20 °C. The apparent Arrhenius parameters, EA, and A, are 22.8 kJ · mol-1 and 3.6 x 107 L · mol-1 · s-1, respectively. These results are divergent from recent literature data.
|Number of pages||6|
|Journal||Macromolecular Rapid Communications|
|Publication status||Published - 18 Sep 2001|