The temperature-dependent transitions of polystyrene-block-poly(ethylene-co-1-butene)-block-poly-styrene 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 degrees C. AFM was employed to study the surface morphology of SEBS and to identify the correlation intensity peaks in the MW2D spectra. The OUT was determined around 152 degrees C. The LDT appears around 170 degrees C. The ODT was also successfully determined around 202 degrees C. It is gained that the key driver of the OUT 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. (C) 2010 Elsevier Ltd. All rights reserved.