Characterization of Polylactides with Different Stereoregularity Using Electrospray Ionization Ion Mobility Mass Spectrometry
- 8 July 2014
- journal article
- Published by American Chemical Society (ACS) in Journal of the American Society for Mass Spectrometry
- Vol. 25 (10), 1771-1779
- https://doi.org/10.1007/s13361-014-0949-1
Abstract
We investigated the effect of stereoregularity on the gas-phase conformations of linear and cyclic polylactides (PLA) using electrospray ionization ion mobility mass spectrometry (ESI-IM-MS) combined with molecular dynamics simulations. IM-MS analysis of PLA ions shows intriguing difference between the collision cross section (ΩD) value of poly-L-lactide (PLLA) and poly-LD-lactide (PLDLA) ions with respect to their chain architecture and stereoregularity. In the singly sodiated linear PLA (l-PLA∙Na+) case, both l-PLLA and l-PLDLA up to 11mer have very similar ΩD values, but the ΩD values of l-PLLA are greater than that of l-PLDLA ions for larger ions. In the case of cyclic PLA (c-PLA), c-PLLA∙Na+ is more compact than c-PLDLA∙Na+ for short PLA ions. However, c-PLLA exhibits larger ΩD value than c-PLDLA for PLA ions longer than 13mer. The origin of difference in the ΩD values was investigated using theoretical investigation of PLAs in the gas phase. The gas-phase conformation of PLA ions is influenced by Na+-oxygen coordination and the weak intramolecular hydrogen bond interaction, which are more effectively formed in more flexible chains. Therefore, the less flexible PLLA has a larger ΩD value than PLDLA. However, for short c-PLA, concomitant maximization of both Na+-oxygen coordination and hydrogen bond interaction is difficult due to the constricted chain freedom, which makes the ΩD value of PLAs in this range show a different trend compared with other PLA ions. Our study facilitates the understanding of correlation between stereoregularity of PLAs and their structure, providing potential utility of IM-MS to characterize stereoisomers of polymers. FigureKeywords
This publication has 53 references indexed in Scilit:
- Polylactic Acid Based Blends, Composites and NanocompositesPublished by Springer Science and Business Media LLC ,2012
- New emerging trends in synthetic biodegradable polymers – Polylactide: A critiqueEuropean Polymer Journal, 2007
- Unambiguous Determination of the 13C and 1H NMR Stereosequence Assignments of Polylactide Using High-Resolution Solution NMR SpectroscopyMacromolecules, 2002
- A Literature Review of Poly(Lactic Acid)Journal of Polymers and the Environment, 2001
- Polylactic Acid TechnologyAdvanced Materials, 2000
- Atmospheric pressure ion mobility spectrometry of protonated and sodiated peptidesRapid Communications in Mass Spectrometry, 1999
- High-Resolution 13C and 1H Solution NMR Study of Poly(lactide)Macromolecules, 1997
- Gas-Phase Conformation of Biological Molecules: BradykininJournal of the American Chemical Society, 1996
- NMR Analysis of Low Molecular Weight Poly(lactic acid)sMacromolecules, 1996
- Plasma ChromatographyAnalytical Chemistry, 1974