Synthesis and characterization of amphiphilic triblock copolymers including β-alanine/α-methyl-β-alanine and ethylene glycol by “click” chemistry

Abstract

Terminally azide poly-β-alanine (PBA-Az) was directly obtained by hydrogen transfer polymerization of acrylamide in the presence of sodium azide as an initiator. However, terminally azide poly(α-methyl β-alanine) (PmBA-Az) was synthesized by the reaction between terminally bromo poly(α-methyl β-alanine) and sodium azide. Dipropargyllated polyethylene glycol (PEG-di-Pr) was synthesized by using the reaction of PEGs with different molecular weights and propargyl bromide. Synthesis of poly(β-alanine-b-ethylene glycol-b-β-alanine) and poly(α-methyl β-alanine-b-ethylene glycol-b-α-methyl β-alanine) amphiphilic ABA triblock copolymers was achieved via “click” chemistry of PBA-Az or PmBA-Az and PEG-di-Pr with different molecular weight. “Click” reaction parameters such as concentration and time were assessed. Macromonomers and the amphiphilic triblock copolymers were characterized by using 1H-NMR, FT-IR, MALDI-MS, TGA, and elemental analysis techniques. The multi-instruments studies of the obtained amphiphilic triblock copolymers reveal that the copolymers easily formed as a result of “click” chemistry.