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-poly urethane-block-poly(methyl methacrylate) triblock copolymers through atom transfer radical polymerization. Number-average molecular weight (M-n) was increased linearly with increasing polymerization time and conversion. Molecular weight distribution becomes narrower as the polymerization time increases and theoretical M-n values of the tri-block copolymers were comparable to the experimental M-n values. Structures of the macroinitiator and the tri-block copolymers were confirmed by H-1 NMR, C-13 NMR and FT-IR spectroscopic techniques. Mole percentage of poly(methyl methacrylate) in the triblock copolymers was calculated using H-1 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.