Cationic polymerization mechanisms

Monomers for manufacture of butyl mbber are 2-methylpropene [115-11-7] (isobutylene) and 2-methyl-l.3-butadiene [78-79-5] (isoprene) (see Olefins). Polybutenes are copolymers of isobutylene and / -butenes from mixed-C olefin-containing streams. For the production of high mol wt butyl mbber, isobutylene must be of >99.5 wt % purity, and isoprene of >98 wt % purity is used. Water and oxygenated organic compounds iaterfere with the cationic polymerization mechanism, and are minimized by feed purification systems. 

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... 

The heats of formation are less suited to characterizing the stability and/or reactivity of carbocations as models of cationic chain ends in cationic polymerizations71). Model reactions closely connected to the cationic polymerization mechanism are better suited to this characterization, for example ... 

K. Matyjaszewski (Ed.), Cationic Polymerizations Mechanisms, Synthesis and Applications, Marcel Dekker, New York, 1996. 

Matyjaszewski K (ed) (1996) Cationic polymerization. Mechanisms, synthesis and applications. Marcel Dekker, New York... 

Solid-state polymerization of D3, initiated by 7-irradiation, has been known for a long time. The reaction proceeds according to the cationic polymerization mechanism.3,5 Solid-state anionic polymerization of hexaphenylcyclotrisi-loxane in the presence of KOH or potassium oligosiloxanolate was recently reported. The crystalline structure of the polymers obtained in high yield in the heterogenous reaction was determined.1... 

Percec, V. Hill, D.H. (1996) In Cationic Polymerization Mechanism, Syntehesis, and Applications, Matyjaszewski, K. Pugh, C., eds. Marcell Dekker, New York. 

Matyjaszewski, K. and C. Pugh, Introduction, Chap. 1 and Mechanistic Aspects of Cationic Polymerization of Alkene, Chap. 3 in Cationic Polymerizations Mechanisms, Synthesis, and Applications, K. Matyjaszewski, ed., Marcel Dekker, New York, 1996. 

Sawamoto, M., Prog. Polym. Sci., 16, 111 (1991) Controlled Polymer Synthesis by Cationic Polymerization, Chap. 5 in Cationic Polymerizations Mechanisms, Synthesis, and Applications,... 

A main feature of the melt polymerization is the sharp increase in electrical conductivity at temperatures (>220°C) where polymerization occurs. This observation together with those described above support a cationic polymerization mechanism based on ionization of a P—Cl bond (Eq. 7-113) followed by electrophilic attack of P+ on monomer (Eq. 7-114). Boron... 

---