Characterization of beta-transition of poly(tert-butyl methacrylate) thin films by two-dimensional infrared correlation spectral analysis

Two-dimensional (2D) correlation analysis has been applied to temperature-dependent FTIR spectra of Langmuir-Blodgett (LB) and spin-coated films of poly(tert-butyl methacrylate) (PtBMA). Synchronous 2D correlation spectra were generated for two temperature regions, i.e. those below and above the glass transition temperature (Tg), to investigate the re-orientation of polymer chain. The autocorrelation analysis revealed that the re-orientation of the bbC-C-O and bbC-C=O bonds connected to chain backbone (bb) and that of the C-O bond of the tert-butoxy group are significant below and above the glass transition temperature, respectively. It is implied strongly from these observations that the simultaneous re-orientation of the chain backbone and the side chain is responsible for the ??-transition of PtBMA.close3