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.