Order–order, lattice disordering, and order–disorder transition in SEBS studied by two-dimensional correlation infrared spectroscopy

The temperature-dependent transitions of polystyrene-block-poly(ethylene-co-1-butene)-block-polystyrene block copolymer (SEBS) at high temperature were studied using infrared spectroscopy combined with two-dimensional (2D) correlation spectroscopy. The order–order transition (OOT), the lattice disordering transition (LDT), and the order–disorder transition (ODT) of SEBS were explored with a linear temperature increment ranging from 100 to 220 °C. AFM was employed to study the surface morphology of SEBS and to identify the correlation intensity peaks in the MW2D spectra. The OOT was determined around 152 °C. The LDT appears around 170 °C. The ODT was also successfully determined around 202 °C. It is gained that the key driver of the OOT is the movements of –CH2– in the main chains of EB blocks. In the LDT, the movements of groups are simultaneous and the SEBS molecular chains move as a whole. In the ODT, it shows the driver is the movements of –CH2– in the main chains of EB blocks.