A Method of Improving the Theoretical Basis of kp Determination from PLP-SEC Measurements

✍ Scribed by Andreas Kornherr; Oskar Friedrich Olaj; Irene Schnöll-Bitai; Gerhard Zifferer

• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: English
• Weight: 109 KB
• Volume: 12
• Category: Article
• ISSN: 1022-1344
• DOI: 10.1002/mats.200390033

✦ Synopsis

Abstract

Making use of hitherto ignored features (such as the peak width) contained in the chain‐length distributions of polymers prepared by pulsed‐laser polymerization (PLP), corrections are calculated from simulated chain‐length distributions for improving the accuracy of the “characteristic chain length” L~0~ data on which the evaluation of the propagation rate constant k~p~ is based. These corrections refer to a wide range of chain lengths and primary radical production, slightly chain‐length‐dependent termination by disproportionation or combination, and a reasonable extent of axial dispersion introduced by the chromatographic device used in the evaluation of the chain‐length distribution. They can be applied to the point of inflection on the low‐molecular‐weight side of the extra peaks as well as to the peak maximum. The remaining mean error which, of course, concerns the evaluation of L~0~ only, is shown to be of the order of 1.0–1.5%, if the mode of termination is unknown, and comes down to about half that value if information on the mode of termination is available. Although all the other errors inherent in the size exclusion chromatography (SEC) method are still present, this method constitutes substantial progress with respect to the accuracy of determining k~p~ data from PLP experiments followed by chromatographic analysis.

Hyper mass distributions calculated for L~0~ = 200, C = 5 and b = 0.16 for termination by disproportionation considering Poissonian and Gaussian broadening.

imageHyper mass distributions calculated for L~0~ = 200, C = 5 and b = 0.16 for termination by disproportionation considering Poissonian and Gaussian broadening.