English Abstract

Metal-Free Living Cationic Polymerization via Carbon-Sulfur Bonds (2)
DT Mechanism Using Thioethers

Mineto UCHIYAMA *1
Kotaro SATOH *1 *2
*1:Department of Applied Chemistry, Graduate School of Engineering, Nagoya University, Chikusa-ku, Nagoya, Japan
*2:Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, Kawaguchi, Saitama, Japan
Nippon Gomu Kyokaishi,(2015),88(12),461-465 General Review in Japanese

This second review on novel metal-free cationic polymerizations is directed to living cationic polymerization that proceeds via reversible activation of carbon-sulfur bonds of thioethers via degenerative chain-transfer (DT) mechanism. In a similar way to cationic RAFT polymerization in the first review, a small amount of triflic acid generates the cationic propagating species, which interchanges with the thioether-dormant species via the sulfonium intermediate stabilized by the sulfur atom, to induce living cationic polymerization via the DT mechanism. This system can similarly control the molecular weight up to 1 ×105 with narrow molecular weight distributions (Mw/Mn< 1.2) and controlled chain-end groups in cationic polymerization of vinyl ethers and p-alkoxystyrene. The thioether-dormant species is highly stable and tolerant in comparison to the dormant species thus far reported in living cationic polymerization. This makes the obtained polymers applicable for subsequent post-polymerization reactions without any significant damages on the C-S bonds.

Keywords: Cationic Polymerization, Living Polymerization, Degenerative Chain Transfer, Vinyl Ether, Styrene, Thioether, Metal-Free System