Regulation of ester contents enabled tunable thermal and mechanical properties of poly(ester amide)

Poly(epsilon-caprolactone-co-epsilon-caprolactam) was synthesized through ring-opening copolymerization of epsilon-caprolactone (CLO) and epsilon-caprolactam catalyzed by ethylmagnesium bromide (EtMgBr) or sodium epsilon-caprolactam. Varied ester contents were achieved from 0 to 100 mol%. EtMgBr enabled the copolymerization with high yield of over 95%. Thermal properties vary with different ester contents. With increasing CLO content, the onset decomposition temperature (273.36 to 240.97 degrees C) and glass transition temperature (52.1 to -56.3 degrees C) gradually decreased. The results of melting behavior of resultant poly(ester amide)s through differential scanning calorimetry and theoretical calculation indicated a eutectic temperature of 46.6 degrees C. The mechanical properties of obtained copolymers were systematically investigated. The enhancement of CLO incorporation led to a decrease in tensile strength (70.99 to 9.88 MPa) and Young's modulus (690.03 to 19.18 MPa). Copolymer with CLO incorporation of 70 mol% exhibited a eutectic temperature of 46.6 degrees C, and enabled a high elongation at break (658%) and enhanced impact strength (138.5 kJ m(-2)). (c) 2023 Society of Chemical Industry.

Automated summary

Poly(epsilon-caprolactone-co-epsilon-caprolactam) was successfully synthesized through ring-opening copolymerization and its thermal and mechanical properties were investigated. The results showed that the thermal properties of the polymer varied with the ester content, and the mechanical properties decreased with increasing epsilon-caprolactone incorporation.