Synthesis and characterization of amphiphilic and hydrophobic ABA-type tri-block copolymers using telechelic polyurethane as atom transfer radical polymerization macroinitiator

Atom transfer radical polymerization of 2-(dimethylamino) ethylmethacrylate and styrene was carried out using tertiary bromine-terminated telechelic polyurethane as a macroinitiator. The resulting ABA-type amphiphilic, poly (2-(dimethylamino) ethylmethacrylate)-b-polyurethane-b-poly (2-(dimethylamino) ethylmethacrylate) and hydrophobic, polystyrene-b-polyurethane-b-polystyrene tri-block copolymers were characterized by spectral, thermal, and chromatographic techniques. As the conversion increases, [`(M)]<sub>textn</sub> {overline M_{_{text{n}}}} also increases linearly. Theoretical M <sub>n</sub> values of the tri-block copolymers were comparable with the experimental [`(M)]_textn {overline M_{_{text{n}}}} values. These results show that the polymerization of styrene and 2-(dimethylamino) ethylmethacrylate occurred through controlled radical polymerization mechanism. Mole percentage of polystyrene and poly (2-(dimethylamino) ethylmethacrylate) blocks in the tri-block copolymers was calculated using proton nuclear magnetic resonance spectroscopy, and the results were comparable with the gel permeation chromatography results. The glass transition temperatures of polystyrene and poly (2-(dimethylamino) ethylmethacrylate) blocks in the tri-block copolymers appeared at 72 °C and 110 °C, respectively. These results confirm the presence of two phases in the tri-block copolymers.