| 초록 |
The phase behavior of polystyrene-block-poly(n-alkyl methacrylate) (PS-PnAMA) copolymer were investigated by temperature-dependent Fourier transform infrared (FTIR) spectroscopy with principal component analysis (PCA) and two-dimensional (2D) correlation spectroscopy. Phase behavior was changed significantly with the change of alkyl number (n). For n = 2~4, only lower disordered-to-order transition (LDOT) was observed, whereas the ordered-to-disorder (ODT) was found for n =1 and n =6. Finally, a closed-loop phase behavior was found for n =5. The phase transition temperatures of all block copolymers were determined by the temperature-dependent FTIR spectra, and these values were very similar to those measured by using SANS, SAXS, rheometry, and depolarized light scattering. Furthermore, information on the conformational changes of specific chemical bonds near the transition could be assessed. For the first time, we showed that the disordered state depended on temperature, implying that the degree of a weak segmental interaction arising from the dipole and induced dipole interactions changed with temperature. Consequently, the driving forces for ordering (or disordering) transitions are different in the two temperature regimes. |
