Polymerization mechanisms, elucidation

Hallpap,P., Bolke, M., and Heublein, G. Elucidation of Cationic Polymerization Mechanism by Means of Quantum Chemical Methods. Vol. 86, pp. 175—236. 

Elucidation of Cationic Polymerization Mechanisms by Means of Quantum Chemical Methods... 

In conclusion, phase transfer catalyzed Williamson etherification and Wittig vinylation provided convenient methods for the synthesis of polyaromatics with terminal or pendant styrene-type vinyl groups. Both these polyaromatics appear to be a very promising class of thermally reactive oligomers which can be used to tailor the physical properties of the thermally obtained networks. Research is in progress in order to further elucidate the thermal polymerization mechanism and to exploit the thermodynamic reversibility of this curing reaction. 

The first part of this report will illustrate how l C-NMR has been utilized in the elucidation of the polymerization mechanisms of cyclic ethers. In the second part, quantitative applications of 13C-NMR for determinations of thermodynamic and kinetic constants will be discussed. The last section deals with possible applications of quantitative 13c-nMR analysis in copolymerization of cyclic ethers. 

A striking feature of the stereoregular polyacetylenes is their simple NMR spectral patterns, which facilitates elucidation of the polymerization mechanism as well as the polymer structure. A co-polymer of phenylacetylene with partly G-labeled phenylacetylene (Ph G= GH) shows two doublet carbon signals with /i3c-i3C of 72 Hz, indicating the presence of G= G bond in the polymer backbone.This is a clear indication of the insertion mechanism instead of the metathesis pathway. 

There are several important reasons for wanting to know molecular weights in polymer science. From the viewpoint of inorganic polymers, the main uses are for the interpretation of molecular-weight dependent properties, and for the elucidation of polymerization mechanisms. The latter involves characterization of the molecular weight distribution, which is the subject of the following section. 

Ring opening polymerization of monocyclic acetals such as 1,3-dioxolane and 1,3-dioxepane has been extensively investigated by several research groups for many years. [6] However, there still remains something to be clarified as to the polymerization mechanisms, particularly the structure of growing species. One of the several reasons that have prevented the elucidation of the polymerization... 

---