MALDI-TOF-MS analysis of living cationic polymerization of vinyl ethers. III. Polymerization with SnCl4 and TiCl4 in the absence of additives

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometr y analysis revealed that the precision control (or the living nature) of th e cationic polymerization of vinyl ethers with SnCl4 or TiCl4 critically de pends on the Lewis acid concentration and temperature. Specifically, at an extremely low Lewis acid concentration, for example, the polymerization wit h the HCl-vinyl ether adduct (an initiator) is living at -78 degreesC in CH 2Cl2 solvent, whereas side reactions occurred at a higher concentration of SnCl4 or at a higher temperature, -15 degreesC. This was more pronounced wi th SnCl4 than with TiCl4, which was due to a stronger Lewis acidity of SnCl 4 as suggested by NMR analysis of the model reactions. (C) 2001 John Wiley & Sons, Inc.