Matrix‐assisted laser desorption/ionization time‐of‐flight mass spectroscopic analysis of telechelic polythiourethanes obtained by the cationic ring‐opening polymerization of six‐membered cyclic thiourethane

Abstract

AbstractA matrix‐assisted laser desorption/ionization time‐of‐flight (MALDI‐TOF) mass spectroscopy analysis of polythiourethanes obtained by the cationic ring‐opening polymerization of a six‐membered cyclic thiourethane [3‐benzyltetrahydro‐1,3‐oxazine‐2‐thione (BTOT)] is described. A MALDI‐TOF mass spectrum of a polymer obtained by the polymerization of BTOT with boron trifluoride etherate (BF3OEt2) as the initiator in nitrobenzene at 50 °C for 24 h followed by an end‐capping reaction with diethyldithiocarbamic acid diethylammonium salt showed a series of well‐resolved signals that were assignable to polythiourethanes possessing an amino group at the initiating end and a diethyldithiocarbamate group at the terminating end. In comparison with the MALDI‐TOF mass spectra of polymers obtained by polymerization with trifluoromethanesulfonic acid or methyl trifluoromethanesulfonate, the plausible initiating species in the polymerization with BF3OEt2 was estimated to be a proton, which successively eliminated carbonyl sulfide to produce a secondary amine group at the initiating end. The secondary amine group in the obtained telechelic polymer was converted to a tertiary amine group by a reaction with benzyl bromide in the presence of triethylamine, and this was confirmed by MALDI‐TOF mass spectroscopy. Furthermore, a telechelic polymer with a pyrrole end group was successfully synthesized by the end‐capping reaction of the growing species in the polymerization of BTOT with sodium 1‐pyrrolecarbodithioate. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4281–4289, 2006