title: Experimental (IR/Raman and 1H/13C NMR) and theoretical (DFT) studies of the preferential conformations adopted by L-lactic acid oligomers and poly(L-lactic acid) homopolymer.
abstract: L-Lactic acid (L-LA) oligomers (up to the pentamer) were studied by three complementary approaches: vibrational (IR and Raman) and NMR ((1)H and (13)C) 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.
authors.affiliation: Department of Chemistry, University of Coimbra, Coimbra, Portugal. sjarmelo@qui.uc.pt
authors.forename: S
authors.initials: S
authors.lastname: Jarmelo
authors.forename: D A S
authors.initials: DA
authors.lastname: Marques
authors.forename: P N
authors.initials: PN
authors.lastname: Simões
authors.forename: R A
authors.initials: RA
authors.lastname: Carvalho
authors.forename: C M S G
authors.initials: CM
authors.lastname: Batista
authors.forename: C
authors.initials: C
authors.lastname: Araujo-Andrade
authors.forename: M H
authors.initials: MH
authors.lastname: Gil
authors.forename: R
authors.initials: R
authors.lastname: Fausto
mesh_terms: D002247:Carbon Isotopes / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry; D019344:Lactic Acid / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008962:Models, Theoretical; D008968:Molecular Conformation; D011091:Polyesters; D011108:Polymers / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013059:Spectrum Analysis, Raman; D013696:Temperature
chemical_list: D002247:Carbon Isotopes; D011091:Polyesters; D011108:Polymers; D019344:Lactic Acid; C033616:poly(lactide); D006859:Hydrogen