|Fundamental Studies and Recent Advances in Anionic Polymerization
1. The Basis of Anionic Polymerization
Polymeric and Organic Materials Department, Graduate School of Science and Engineering, Tokyo Institute of Technology H-127, Meguro-ku, Tokyo, Japan
Nippon Gomu Kyokaishi,(2006),79(11),543-549 General Review in Japanese
As a general introduction to anionic polymerization, this paper will review the categorization of anionic initiators and vinyl monomers according to Q-e values, the nature of carbanions in solution, especially their interaction with counter ions, the controlling of stereochemistry from 1,3-diene and alkyl methacrylate polymerizations, and the basics of ring-opening polymerization. Vinyl monomers are categorized into four groups according to Q-e values. The anionic polymerizable monomers with higher Q values than 0.2 depend on their e values relating to the electron density on vinyl groups. The polymerization of high reactive monomers can be initiated with weak nucleophiles, while strong nucleophiles are required to initiate the polymerization of low reactive monomers. On the other hand, the relationship between reactivities of monomers and their active chain ends is basically inverse order. In order to understand the kinetics and mechanisms of anionic polymerization, the equilibriums among of the contact ion pair, the solvent separated ion pair, and free ion are discussed in terms of the reactivity of polystyryl anions. The dependence of stereochemistry of 1,3-diene monomer and alkyl methacrylate polymerizations on the counter cation, solvent, and additive is described.
Anionic Polymerization, Ring-opening Polymerization, Anionic Initiator, Monomer, Q-e values, Microstructure, Tacticity, Elastomer