High-yield synthesis of functionalized alkoxyamine initiators and approach to well-controlled block copolymers using them

Reaction of ethylbenzene, 4-bromo-, 4-(ethoxycarbonyl)-, and 4-methoxyethylbenzenes with di-tert-butyl diperoxyoxalate at 35 degrees C in the presence of stable nitroxide radicals gave alkoxyamines in 50-91% yields. Lithiation of the 4-bromophenylalkoxyamine and subsequent treatment with DMF gave 4-formylphenylalkoxyamine in 95% yield, and the reduction of the 4-formylphenylalkoxyamine with NaBH(4) yielded 4-(hydroxymethyl)phenylalkoxyamine in 89% yield. Anionic polymerization of butadiene (BD) with sec-BuLi and subsequent termination with 4-formylphenylalkoxyamine gave an end-functionalized poly(butadiene) [poly(BD)]. "Living" radical polymerization of styrene (St) initiated by the functionalized poly(BD) at 120 degrees C gave a poly(BD)-block-poly(St) with a M(w)/M(n) of 1.30. Anionic polymerization of hexamethylcyclotrisiloxane (D(3)) with 4-lithiophenylalkoxyamine gave poly(D(3)) with an alkoxyamine moiety at a polymer end. "Living" radical polymerization of St initiated by the functionalized poly(D(3)) gave poly(D(3))-block-poly(St) with M(w)/M(n)'s of 1.73-1.80.