Novel polyesteramides-based diblock copolymers: synthesis by ring-opening copolymerization and characterization

Block copolymers based on a polyesteramide sequence and a polyether block were synthesized in bulk at 250?°C by ring-opening copolymerization (ROP) of e-caprolactone (CLo) and e-caprolactam (CLa) as initiated by Jeffamine® M1000, i.e., ?-NH2 copoly[(ethylene oxide)-co-(propylene oxide)] copolymer [P(EO-co-PO)-NH2]. For an initial molar ratio of [CLa]0/[CLo]0?=?1, the copolymerization allowed for the formation of a diblock copolymer with a statistical polyesteramide sequence, as evidenced by 13C NMR. Investigation of the ROP mechanism highlighted that CLo was first polymerized, leading to the formation of a diblock copolymer P(EO-co-PO)-b-PCLo-OH, followed by CLa hydrolysis to aminocaproic acid that inserted into the ester bonds of PCLo via aminolysis and subsequent condensation reactions. The outcome is the selective formation of P(EO-co-PO)-b-P(CLa-co-CLo)-OH diblock copolymers where the composition and length of the polyesteramide sequence can be fine-tuned by the [CLa]0/[CLo]0 and ([CLa]0?+?[CLo]0)/[P(EO-co-PO)-NH2]0 initial molar ratios.