Synthesis of polystyrene-b-polyurethane-b-polystyrene tri-block copolymers through ARGET ATRP polymerization method. Part I. Synthesis of macroinitiator and polymerization mechanism

The polystyrene-b-polyurethane-b-polystyrene (PS-b-PUR-b-PS) tri-block copolymers were synthesized for the first time using ARGET ATRP method. Aspecially prepared for this purpose bromourethane macroinitiator (MBP-PUR-MBP) was used as an intermediate product reacting with styrene in the presence of CuBr2 catalyst and N,N,N',N",N"-pentamethyldiethylenetriamine (PMDETA) as a complexing agent. It was found that both the molecular weight of the resulting copolymer versus styrene conversion as well as the value of ln([M]0/[M]) as afunction of polymerization time increase linearly. High values of the linear correlation coefficients for the studied relationships indicate that the formation of tri-block copolymers takes place according to ATRP mechanism.