Characterization of spin-coated films of biodegradable poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymers by two-dimensional correlation spectroscopy

Principal component analysis-based two-dimensional (PCA2D) correlation spectroscopy combined with the eigenvalue manipulating transformation (EMT) technique by lowering the power of a set of eigenvalues associated with the original data was applied to the temperature-dependent infrared-reflection absorption (IRRAS) spectra of spin-coated films of biodegradable P(HB-co-HHx) (HHx = 3.8, 7.2, and 10.0 mol%) copolymers. The PCA2D correlation spectra for P(HB-co-HHx) (HHx = 10.0 mol%) copolymer is completely different from those for P(HB-co-HHx) (HHx = 3.8 and 7.2 mol%) copolymers. In the synchronous PCA2D correlation spectra, the intensity changes of the bands at 1136 and 1282 cm−1 changed greatly as HHx mol% of P(HB-co-HHx) copolymers increases. Furthermore, EMT technique accentuates the contribution of intensity of band enhanced the minor PCs, seems to preferentially emphasizes the behavior of amorphous components of during the heating process.