Parametric Analysis of the Intermediate Concentration in a RAFT Polymerization and its Influence upon the Polymerization Kinetics

✍ Scribed by Alessandro Butté; A. David Peklak

• Publisher: John Wiley and Sons
• Year: 2006
• Tongue: English
• Weight: 579 KB
• Volume: 15
• Category: Article
• ISSN: 1022-1344
• DOI: 10.1002/mats.200600005

✦ Synopsis

Abstract

Summary: A kinetic analysis of living/controlled radical polymerizations in bulk mediated by RAFT is presented. The main objective is to show how the kinetics of the RAFT process and, in particular, of the RAFT intermediate radical is affecting the overall polymerization rate. Namely, three different cases are analyzed: (i) slow fragmentation of the RAFT intermediate; (ii) cross‐termination of the RAFT intermediate with other radicals; and (iii) slow re‐initiation of the RAFT agent leaving group. Simplified analytical formulas are derived for the time‐dependent concentrations of the involved species as well as for conversion. They are supported by numerical simulations and are qualitatively compared to literature experimental findings. Criteria are also given to judge the influence of the RAFT reaction kinetic rate constants on the different phenomena observed experimentally in RAFT polymerization, namely inhibition and retardation. Since these criteria are given by using non‐dimensional groups, they can be readily applied to a broad spectrum of experimental conditions.

Logarithmic non‐dimensional concentration for the radicals (r) and intermediate radicals (q) versus the non‐dimensional polymerization time ($\tau$).

magnified imageLogarithmic non‐dimensional concentration for the radicals (r) and intermediate radicals (q) versus the non‐dimensional polymerization time ($\tau$).