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Pseudostationary Polymerization: Improving the Determination of the Rate Constant of Propagation
Author(s) -
Zifferer Gerhard,
Kornherr Andreas,
SchnöllBitai Irene,
Olaj Oskar Friedrich
Publication year - 2004
Publication title -
macromolecular symposia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.257
H-Index - 76
eISSN - 1521-3900
pISSN - 1022-1360
DOI - 10.1002/masy.200451324
Subject(s) - polymerization , constant (computer programming) , dispersion (optics) , gaussian , materials science , chain propagation , analytical chemistry (journal) , chemistry , molecular physics , optics , physics , chromatography , polymer , computational chemistry , computer science , programming language , composite material
Pulsed‐laser initiated polymerization (PLP) leads to chain length distributions with characteristic extrapeaks. The low molecular weight side points of inflection L LPI are located near to (multiples) of a specific chain length L 0 which is equal to the product of pulse separation t 0 and propagation frequency k p [ M ], i.e. rate constant of propagation k p times monomer concentration [ M ], allowing a direct determination of k p . However, Poissonian broadening inherent in the polymerization process as well as Gaussian broadening due to axial dispersion caused by the size exclusion chromatographic (SEC) device leads to a shift of L LPI as compared to L 0 – its extent depending on the experimental parameters chosen – which in turn causes an error up to 10–20% in the rate constants evaluated. Fortunately, comparison of the experimental peak width with some sort of theoretical peak width yields several types of correction factors and furthermore master‐correction functions which are able to reduce the remaining error on average by at least a factor of 10.