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

Abstract

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 ( T g), to investigate the re-orientation of polymer chain. The autocorrelation analysis revealed that the re-orientation of the bb C C O and bb C 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 β-transition of PtBMA.