Telechelic Multifunctional Polyurethane-Based Macroinitiator for the Synthesis of Polystyrene-block-Polyurethane-block-Polystyrene Tri-Block Copolymers via Atom Transfer Radical Polymerization

摘要

Atom transfer radical polymerization was successfully used to synthesize polystyrene-b-polyurethane-b-polystyrene tri-block copolymers (PSt-b-PU-b-PSt) using telechelic multifunctional polyurethane (Br3C-PU-CBr3) as a macroinitiator. Along with macroinitiator, CuBr and N,N,N',N'',N''-pentamethyldiethyltetramine (PMDETA) were also used as catalyst and ligand, respectively to polymerize styrene. The linear increase of [image omitted] with conversion shows that Br3C-PU-CBr3/CuBr/PMDETA initiating system polymerizes styrene through controlled radical polymerization mechanism. Mole ratio of polyurethane and polystyrene present in PSt-b-PU-b-PSt tri-block copolymers was calculated using proton nuclear magnetic resonance spectroscopy and the results were found to be comparable with the gel permeation chromatography results. Differential scanning calorimetric results confirmed the presence of polyurethane and polystyrene phases in the tri-block copolymers.