Projection 2D correlation analysis of spin-coated film of biodegradable P(HB-co-HHx)/PEG blend

We investigated thermal behavior of spin-coated film of P(HB-co-HHx)/PEG blend by using infrared-reflection absorption (IRRAS) spectroscopy, 2D correlation spectroscopy, and projection 2D correlation analysis. From the analysis of 2D IRRAS correlation spectra, we could determine the sequence of spectral intensity changes with increasing temperature that PEG band changes first, and then a band for crystalline component of P(HB-co-HHx) changes before a band for amorphous component. Null-space 2D projection correlation spectra clearly showed the contribution of PEG in spin-coated film of P(HB-co-HHx)/PEG blend during heating process, which is barely observable in conventional 2D IRRAS correlation spectra. Projection and null-space projection 2D correlation analysis seem to selectively accentuate the subtle contribution of thermal behavior of PEG in spin-coated film of P(HB-co-HHx)/PEG blend during heating process.