In this work, both 1D and 2D ATR-FTIR analyses were applied to study the behaviors of the PEO–PPO–PEO tri-block copolymer (Pluronic-F88) aqueous solution during the thermal gelling process. Furthermore, a novelly synthesized phosphorylcholine-modified F88 was also studied by the same technique, for the explanation to its different performance in the rheological study, as compared to F88. It was mainly focused on the changes in the water structure between sol and gel states, and the interactions between chemical bonds in the polymer chains with water molecules at a molecular level.