Facile metal‐free living cationic polymerization of various vinyl ethers by hydrogen chloride with ether

Useful metal-free living cationic polymerization of various vinyl ethers by hydrogen chloride with ether was found for the first time. This system is facile polymerization using not HCl/Lewis acid but HCl alone in ether (Et2O) without Lewis acid. The molecular weights of the obtained polymers can be controlled with the feed ratio of the monomer and HCl. Furthermore, after-treatment can be easily carried out, because the system is inherently free from contaminants from metal catalyst residues. The living polymerization also can be achieved at relatively higher temperature for cationic polymerization. The key to success of living cationic polymerization in the system is using HCl·Et2O and controlling the polymerization temperature.