Synthesis of multiblock thermoplastic elastomers based on biodegradable poly (lactic acid) and polycaprolactone

A new biodegradable (AB)n type of multiblock copolymers derived from poly (ε-caprolactone) (PCL) and poly (lactic acid) (PLA) was prepared via the method of the chain extending reaction among PCL oligomers, PLA oligomers and hexamethylene diisocyanate (HDI). Fourier transform infrared spectra (FTIR), 1H NMR, thermal gravity analysis (TGA) and derivative thermograms (DTG) were used to characterize the copolymers and the results showed that PCL and PLA were coupled by the reaction between –NCO groups and terminal –OH and –COOH groups of PCL and PLA, respectively. The material displayed enhanced mechanical properties: Young's modulus was as low as 2.7 ± 0.7 MPa and elongation at break value was above 790% at the composition of PCL/PLA = 80/20 (w/w). Moreover, according to SEM micrographs interfacial adhesion of the composites was improved. Thermal degradation temperature of the composites was higher than PLA but was lower than PCL, which is an advantage for industry process