Syntheses of well-defined poly(siloxane)- b-poly(styrene) and poly(norbornene)- b-poly(styrene) block copolymers using functional alkoxyamines

Abstract

Functional alkoxyamines, 1-[4-(4-lithiobutoxy)phenyl]-1-(2,2,6,6-tetramethylpiperidinyl- N-oxyl)ethane ( 2) and 1-[4-(2-vinyloxyethoxy)phenyl]-1-(2,2,6,6-tetramethylpiperidinyl- N-oxyl)ethane ( 3) were prepared, and well-defined poly(hexamethylcyclotrisiloxane)- b-poly(styrene)[poly(D 3)- b-poly(St)] and poly(norbornene)- b-poly(St) [poly(NBE)- b-poly(St)] were prepared using the alkoxyamines. The first step was preparation of poly(D 3) and poly(NBE) macroinitiators, which were obtained by the ring-opening anionic polymerization of D 3 using 2 as an initiator and the ring-opening metathesis polymerization of NBE using 3 as a chain transfer. The radical polymerization of St by the poly(D 3) and poly(NBE) macroinitiators proceeded in the ‘living’ fashion to give well-defined poly(D 3)- b-poly(St) and poly(NBE)- b-poly(St) block copolymers.