Synthesis of Amphiphilic Diblock and Random Copolymers of Styrene and N-Vinylpyrrolidone using Nitroxide-mediated Living Free Radical Polymerization

Living polymerization of styrene initiated with benzoyl peroxide (BPO) in the presence of 2,2,6,6-tetramethyl piperidine-N-oxyl (TEMPO) at 125°C was performed by using nitroxide-mediated living radical polymerization (NMRP) technique. The obtained TEMPO-ended polystyrene served as macroinitiator for the synthesis of poly(styrene-block-vinylpyrrolidone) diblock copolymer. Also, by polymerization of the mixture of styrene and N-vinylpyrrolidone in the presence of TEMPO and BPO, random copolymers of these monomers were prepared at different feed ratios by NMRP technique. The microstructure of synthesized polymers is investigated by 1HNMR and IR spectroscopies and GPC techniques. The compositions of synthesized polymers were investigated by elemental analysis and the reactivity ratios of these monomers were calculated by using the elemental analysis data through Fineman-Ross equation, which were 15.509 and 0.102 for styrene and N-vinylpyrrolidone, respectively. The solubility of synthesized diblock and random copolymers are investigated in various solvents, and the results showed the amphiphilicity of synthesized copolymers.