Journal of Physical Chemistry B, Vol.116, No.1, 9-21, 2012
Experimental (IR/Raman and H-1/C-13 NMR) and Theoretical (DFT) Studies of the Preferential Conformations Adopted by L-Lactic Acid Oligomers and Poly(L-lactic acid) Homopolymer
L-Lactic acid (L-LA) oligomers (up to the pentamer) were studied by three complementary approaches: vibrational (IR and Raman) and NMR (H-1 and C-13) spectroscopies and DFT calculations. Vibrational and NMR spectra of L-LA oligomers and poly(L-lactic acid) (PLLA) homopolymer were recorded at room temperature and interpreted. Further insight into the structures (conformations) of the title systems was provided by theoretical B3LYP/6-311++G(d,p) studies. Calculated energies and computed vibrational and NMR spectra of the most stable conformers of L-LA oligomers, together with the experimental vibrational and NMR spectra, enabled the characterization of the preferred conformations adopted by PLLA chains.