Study on the mechanism of hydrogen bonding interactions between poly(vinyl alcohol) and ionic liquid

The combination of ionic liquids (ILs) with polymers have attracted mushroom attention due to their complementary advantages. Hydrogen bonding interactions is usually responsible for the final properties of the obtained polymer/IL products. In this study, the interactions between an IL 1-(2-hydroxyethyl)-3-methylimidazolium chloride ([HOEtMIM]Cl) and poly(vinyl alcohol) (PVA) have been investigated in detail by using in situ FTIR spectroscopy. In addition, two-dimensional (2D) correlation infrared spectroscopy and perturbation correlation moving-window two-dimensional (PCMW2D) technique were also employed to study the microdynamics mechanism. Hydrogen bonding interactions of PVA-IL is highly dependent on the ILs content and the temperature. Hydrogen bonds of PVA itself dominated in the system at a low ILs content of 15 wt%. However, with increasing ILs content, hydrogen bonding interactions of PVA-ILs gradually played a major role within PVA/IL system. It was also demonstrated that hydrogen bonds between PVA and ILs interacted most strongly in the temperature range of 81-120 degrees C.PVA/IL system is thermodynamically compatible without phase behavior, as evidenced by DMA and optical microscopy test. This research work provides a new strategy for the performance adjustment of PVA/IL materials at the theoretical level, allowing fine-tuning of their physicochemical properties for new applications in various fields such as energy storage, sensors, and actuators.