A spectroscopic analysis of chain flexibility of poly(lactic acid)

A Raman analysis was conducted to examine the disordered structures of poly(lactic acid). Simulated spectra were obtained for an ensemble of chains generated by several rotational isomeric state models. Analysis of the differences between simulated and experimental spectra showed that the rotational isomeric state reported in earlier work leads to a chain that is much more flexible than the experimental data suggest. The Raman analysis suggests a chain dominated by tgt conformations in a 3(1) helix with a characteristic ratio of 12, consistent with other experimental data.