THE POSSIBILITY OF LIVING OR LONG-LIVED CATIONIC POLYMERIZATION IN THE BUTYL VINYL ETHER IODINE LIQUID SULFUR-DIOXIDE SYSTEM

The polymerization of butyl vinyl ether (nBuVE) initiated by iodine in the presence of liquid sulfur dioxide has been investigated. The numb er-average molecular weight increased with monomer concentration and a fter the addition of a fresh feed of the monomer at the end of the fir st polymerization step. This behavior has been observed in media of di fferent polarity, that is, SO2/toluene = 80:10 or 50:40 v/v and SO2/CH 2Cl2 = 20:70 v/v. H-1 NMR spectroscopy revealed the presence of aldehy de terminal group derived from acetal end group, indicating the presen ce of living or long-lived propagating species. The average number of polymer chains carrying aldehyde end groups is higher than the initial iodine concentration, suggesting that an additional initiation proces s by hydrogen iodide is taking place.