Halogen-Bonding-Mediated and Controlled Cationic Polymerization of Isobutyl Vinyl Ether: Expanding the Catalytic Scope of 2-Iodoimidazolium Salts

4 years ago

Halogen-Bonding-Mediated and Controlled Cationic Polymerization of Isobutyl Vinyl Ether: Expanding the Catalytic Scope of 2-Iodoimidazolium Salts

Koji Takagi, Hiroto Murakata, Koji Yamauchi

Metal-free initiating systems for living cationic polymerizations are desirable from the viewpoint of environmentally benign polymer synthesis. We describe here the development of a halogen-bonding-mediated and controlled cationic polymerization of isobutyl vinyl ether (IBVE) using 2-iodoimidazolium salts as an organocatalyst. Due to the ionic nature of the catalysts, the polymerization should be performed in CH2Cl2. The HCl-adduct of IBVE was the most suitable initiator, and the polymerization was carried out at −10 °C under the catalyst concentration of 10 mm to suppress alcohol elimination from the polymer chain. The addition of a small amount of nBu4NCl (0.02 equivalent) was effective to accomplish the controlled cationic polymerization and obtain polyIBVE, having the molecular weight distribution below 1.3. Polymers through XB catalysis: Metal-free controlled cationic polymerization of isobutyl vinyl ether (IBVE) was accomplished using halogen-bonding (XB) organocatalysts. 2-Iodoimidazolium salts enabled the carbon-halide bond scission at the propagating end to give polyIBVE with narrow molecular weight distribution. The addition of a small amount of nBu4NCl was effective to achieve a controlled polymerization.

Publisher URL: http://onlinelibrary.wiley.com/resolve/doi

DOI: 10.1002/chem.201702455