Effect of poly(D-lactic acid) and cooling temperature on heat resistance and antibacterial performance of stereocomplex poly(L-lactic acid)

Stereocomplex nucleated polylactic acid was prepared by the addition of poly(D-lactic acid) (PDLA) in poly(L-lactic acid) (PLLA) under various cooling temperatures by monitoring the mechanical properties and heat resistance. Antibacterial performance against the growth of Escherichia coli on PLLA/PDLA doped with various contents of 2-hydroxypropyl-3-piperazinyl-quinoline carboxylic acid methacrylate (HPQM) was also evaluated. The results suggested that a small addition of PDLA generated stereocomplex crystals while increasing cooling temperature resulted in homo crystals formation in PLLA. The incorporation of PDLA with high cooling temperature increased the heat deflection temperature, impact resistance, and tensile modulus, but decreased the antibacterial performance against E. coli. The addition of PDLA at 2.0 wt% in PLLA at cooling temperature at 80 degrees C showed a synergistic effect to obtain an exceptionally high heat deflection temperature up to 164 degrees C. HPQM was, for the first time, introduced as antibacterial agent in PLLA with an optimum dosage of 1750 ppm. (c) 2020 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48970.