Determination of Percent crystallinity of Side-Chain Crystallized Alkylated-Dextran Derivatives with Raman Spectroscopy and Multivariate Curve Resolution

We have developed a new self-consistent method for determining the absolute percent crystallinity of polymers directly with Raman spectroscopy. We estimate the ratio of the Raman cross-sections (ftrans/fgauche) of the trans and the gauche conformers assuming a two-state phase-transition model. Using the determined ratio (0.74±0.04), we estimate the absolute percent crystallinity of alkylated dextran derivatives with an accuracy of ~1%. The number of carbons in the crystalline lattice has also been estimated from the position of longitudinal acoustic (LA) Raman bands with the correlation established by Mizushima and Shimanouchi. The new method allows direct Raman estimation of absolute percent crystallinity of polymers, which until now, was possible only in conjunction with other techniques or by using internal standards.