The Mechanism of the Self-Initiated Thermal Polymerization of Styrene. Theoretical Solution of a Classic Problem

The Mayo and Flory mechanisms for the self-initiation of styrene polymerization were explored with B3LYP and BPW91 density functional calculations. The Diels−Alder dimer (AH) is the key intermediate, and the lowest energy pathway for AH formation is a stepwise mechanism via a gauche/sickle (• M 2 •...

Full description

Saved in:
Bibliographic Details
Published in:Journal of the American Chemical Society 2005-02, Vol.127 (4), p.1265-1277
Main Authors: Khuong, Kelli S, Jones, Walter H, Pryor, William A, Houk, K. N
Format: Article
Language:English
Subjects:
Applied sciences
Exact sciences and technology
Organic polymers
Physicochemistry of polymers
Polymerization
Preparation, kinetics, thermodynamics, mechanism and catalysts
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The Mayo and Flory mechanisms for the self-initiation of styrene polymerization were explored with B3LYP and BPW91 density functional calculations. The Diels−Alder dimer (AH) is the key intermediate, and the lowest energy pathway for AH formation is a stepwise mechanism via a gauche/sickle (• M 2 • Gs) or gauche/U-shaped (• M 2 • Gu) diradical. Ring closure of the 1,4-diradical to diphenylcyclobutane (DCB) is predicted to have a lower barrier than ring closure to AH. Dynamic effects are likely to play an important role in determining the rate of AH versus DCB formation. Hydrogen transfer from AH to styrene to generate two monoradical species is predicted to be a reasonable process that initiates monoradical polymerization.
ISSN:0002-7863
1520-5126
DOI:10.1021/ja0448667