Broadband terahertz spectroscopy of enantiomeric polylactide

Abstract In this study, poly (L-lactide) (PLLA), (D-lactide) (PDLA), and their blend (stereocomplex; SC) were investigated by terahertz spectroscopy. Absorption spectra obtained for PLLA isothermally crystallized in a temperature range of 80 °C–140 °C, eight characteristic peaks observed the frequency 1–15 THz. No obvious spectral difference between PDLA was observed, indicating that chirality did not affect spectra. Conversely, SC sample exhibited complex peak shift behavior different from those homo-crystals. To elucidate origins vibration modes, measurement lactide conducted compared with results PLLA. Four absorption appeared below 8 THz disappeared experimental lactide. This suggests modes polylactide differ around THz, low higher frequencies are attributed to inter- intramolecular respectively.