Cationic ring-opening polymerization of monothiocarbonate with a norbornene group

This work deals with the cationic ring-opening polymerization of cyclic thiocarbonates with a norbornene or norbornane moiety, that is, 5,5-(bicyclo[2.2.1]hept-2-ene-5,5-ylidene)-1,3-dioxane-2-thione (TC1) or 5,5-(bicyclo[2.2.1]heptane-5,5-ylidene)1,3-dioxane-2-thione (TC2), respectively. The reaction of TC1 initiated by trifluoromethanesulfonic acid (MOH), methyl trifluoromethanesulfonate (TfOMe), boron trifluoride etherate (BF3OEt2), or triethyloxonium tetrafluoroborate (Et3OBF4) afforded unidentified products; however, TC1 underwent cationic ring-opening polymerization with methyl iodide as an initiator to afford polythiocarbonate because the propagating end was stabilized by the covalent-bonding property. The polymerization of TC2 initiated by TfOH, TfOMe, BF3OEt2, or Et3OBF4 afforded polythiocarbonate with good solubility in common organic solvents and a narrow molecular weight distribution because of the absence of a double-bond moiety. (C) 2002 Wiley Periodicals, Inc.