New N-alkoxyamine initiators were synthesized containing the highly versatile thiol group. A tert-butyldimethylsilyl protected monodirectional initiator was synthesized as well as a disulfide linked bidirectional initiator. Both initiators were used in nitroxide-mediated radical polymerization with styrene; additionally, the disulfide bidirectional initiator was used to polymerize dimethylacrylamide. Polymer chains bearing a terminal silyl protected thiol were deprotected and oxidized resulting in polymers with double the molecular weight. Alternately, polymers grown from the bidirectional initiator bearing a central disulfide linkage were reductively cleaved, resulting in a halving of molecular weight. The manipulation of the thiol group and the reversible disulfide linkage at the polymer terminus offers potential for applications in nanotechnology. (c) 2007 Elsevier Ltd. All rights reserved.