Synthesis of thiol end-functional polystyrene via atom transfer radical polymerization

Polymers obtained by Atom Transfer Radical Polymerization (ATRP) possess an omega-halogen end-group that may be converted to other functional groups by appropriate chemical transformations. Here we report a versatile new method for end-functionalizing polymers with a thiol. The bromine end-group of the polystyrene obtained from ATRP is converted into an isothiouronium salt by reaction with thiourea. Subsequent treatment of this salt with a base permits the cleavage to a thiol. This method allows the preparation of thiol functional polystyrene of narrow polydispersity with a high degree of functionalization and control of the molecular weight. (C) 2003 Elsevier Science B.V. All rights reserved.