Principal component analysis-based two-dimensional (PCA2D) correlation spectroscopy through eigenvalue manipulating transformation (EMT) of spectral data set was applied to temperature-dependent IR spectra of polystyrene-block-poly(n-pentyl methacrylate) (PS-PnPMA) for spectral selectivity enhancement. EMT technique which uniformly lowers the power of a set of eigenvalues associated with the original data highlights the subtle contributions from minor eigenvectors. Thus subtle differences in the thermal responses of PS-PnPMA, which are difficult to observe by conventional 2D correlation analysis, are accentuated much more strongly than the original data. A conclusion was reached on details of phase transition of PS-PnPMA which exhibited a closed-loop phase behavior bounded by a lower disorder-to-order transition (LDOT) and an upper order-to-disorder transition (UODT). We found that a disordered state at lower temperature is different from that at higher temperature.
Bibliographical noteFunding Information:
This work was supported by the National Creative Research Initiative Program supported by KOSEF. Y.M. Jung acknowledges the support from the Korea Research Foundation Grant funded by the Korean Government (MOEHRD) (KRF-2005-204-C00031).
All Science Journal Classification (ASJC) codes
- Analytical Chemistry
- Organic Chemistry
- Inorganic Chemistry