Vibrational analysis of poly(L‐lactic acid)

Abstract

The Raman and IR spectra of poly(L-lactic acid) in the amorphous and semicrystalline states were recorded from 3600 to 100 cm-'. Complete vibrational assignments are proposed. In the Raman spectra, the splittings of the vC=O stretching and the SCCO bend are characteristic of the crystalline phase and the presence of the two lines at 923 and 520 cm-' indicates a 10, helical conformation.

Vibrational spectroscopy of polymeric biomaterials

“…Vibrational studies on the ring-opening polymerization of L-lactide and D,L-lactide, 10 on L-lactic and D,L-lactic acid oligomers 11 and on the morphology, conformation and configuration of various PLAs 12,13 have been reported. Since lactic acid is a chiral compound, different stereocopolymers can be obtained; high or low molecular weight, semi-crystalline or amorphous, isotactic, syndiotactic or atactic polymers can be synthesized depending on the polymerization method (conditions and starting materials).…”

“…Since lactic acid is a chiral compound, different stereocopolymers can be obtained; high or low molecular weight, semi-crystalline or amorphous, isotactic, syndiotactic or atactic polymers can be synthesized depending on the polymerization method (conditions and starting materials). 12,13 Raman spectroscopy is suitable for qualitatively and quantitatively evaluating the extent of conformational and configurational isomerisms from band assignments and the degree and nature of crystalline and non-crystalline order from the intensities of the assigned bands. 12,13 In particular, for the quantitative determination of PLA crystallinity, partial least squares (PLS) analysis has been successfully used for correlating the crystallinity of the polymer with the Raman spectrum.…”

“…12,13 Raman spectroscopy is suitable for qualitatively and quantitatively evaluating the extent of conformational and configurational isomerisms from band assignments and the degree and nature of crystalline and non-crystalline order from the intensities of the assigned bands. 12,13 In particular, for the quantitative determination of PLA crystallinity, partial least squares (PLS) analysis has been successfully used for correlating the crystallinity of the polymer with the Raman spectrum. 14 Complete vibrational assignments were proposed for PLA 100 (in the acronym PLA x , x represents the percentage of L-lactic acid units) in the amorphous and semicrystalline (crystallinity of about 73%) states 12,13 as well as for PLAcomplex (formed by PLA 100 and PLA 0 ) and different amorphous PLA 50 s (preferentially isotactic, preferentially syndiotactic and atactic).…”

“…13 The Raman-active modes most sensitive to modifications in chain morphology were identified as C O, υCCO, C O and skeletal stretchings. 12,13 The presence of the two bands at 923 cm 1 ( CH 3 C CC) and 520 cm 1 (υ s CCH 3 C υCCO) in the spectrum of semi-crystalline PLA 100 indicated a 10 3 helical conformation, 12,13 while the 908 cm 1 band ( CH 3 C CC) in the spectrum of PLAcomplex revealed the presence of the 3 1 helix. 13 The splitting of the C O mode (with strong components, in semi-crystalline PLA 100 , at 1750, 1763, 1769 and 1773 cm 1 corresponding to A, B, E 1 and E 2 species modes) and of the υCCO mode (with two sharp components at 410 and 398 cm 1 , in semi-crystalline PLA 100 and PLAcomplex) were identified as characteristic of the crystalline phase.…”

Low temperature formation of calcium-deficient hydroxyapatite-PLA/PLGA composites

“…These data have been obtained from a number of sources. [44][45][46] The FTIR data reveal that there is no change in the structure of the PLGA copolymer during the hydrolysis of TCP. The shapes and positions of the characteristic bands for the co-polymer, indicated by the triangles in Figure 3, are the same for both spectra.…”