Vinyl ethers and oxetanes was successfully polymerized cationically in carbon dioxide. These processes become heterogeneous using hydrocarbon vinyl ethers and oxytanes but high molar mass and high conversions can still be achieved. Homogeneous cationic polymerization are also possible with fluorocarbon-based alkyl vinyl ether and oxetane monomers. Polymerization occurs without incorporation of carbon dioxide into the polymer backbone for the systems used.