Ab Initio Study of Poly(vinyl chloride) Propagation Kinetics: Head-to-Head versus Head-to-Tail Additions
✍ Scribed by Karen Van Cauter; Veronique Van Speybroeck; Michel Waroquier
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 606 KB
- Volume
- 8
- Category
- Article
- ISSN
- 1439-4235
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✦ Synopsis
Abstract
The relative importance of head‐to‐head versus head‐to‐tail additions during the free‐radical polymerization of vinyl chloride is determined by ab initio methods for different chain lengths of the polymer. First, a level of theory study is performed to determine cost‐effective methods for the ab initio description of the propagation kinetics of vinyl chloride. The study includes the following DFT‐based methods: B3LYP, B3PW91, BHandH, BHandHLYP, BLYP, BP86, MPW1K and MPW1PW91, in combination with double or triple zeta basis sets 6‐31G(d) and 6‐311G(d,p). Also, the more recently developed BMK and MPW1K functionals are included. The influence of diffuse functions is tested by comparison with the basis sets 6‐31+G(d) and 6‐311++G(3df,2p). The best‐performing methods are B3LYP, B3PW91 and MPW1 K combined with the 6‐31+G(d) basis set. The converged probability of head‐to‐head propagation (2 per 1000 monomer units) is put into relation with the experimental concentrations of defect structures. A comparison is made with the head‐to‐head (HH) content of fluorine‐substituted polymers and poly(vinyl acetate). The ab initio calculations correctly predict the relative sequence of HH content among the various polymers.