Novel Telechelic 2-Methyl-2-Bromopropionate Terminated Polyurethane Macroinitiator for the Synthesis of ABA type Tri-block Copolymers through Atom Transfer Radical Polymerization of Methyl Methacrylate

Novel telechelic 2-methyl-2-bromopropionate terminated polyurethane macroinitiator was synthesized and used further to polymerize methyl methacrylate to yield poly(methyl methacrylate)-block-polyurethane-block-poly(methyl methacrylate) tri-block copolymers through atom transfer radical polymerization. Number-average molecular weight (Mn) was increased linearly with increasing polymerization time and conversion. Molecular weight distribution becomes narrower as the polymerization time increases and theoretical Mn values of the tri-block copolymers were comparable to the experimental Mn values. Structures of the macroinitiator and the tri-block copolymers were confirmed by 1H NMR, 13C NMR and FT-IR spectroscopic techniques. Mole percentage of poly(methyl methacrylate) in the triblock copolymers was calculated using 1H NMR spectroscopy and was found to be comparable with the gel permeation chromatography results. Presence of two phases in the tri-block copolymers has been confirmed through differential scanning calorimetric studies.