화학공학소재연구정보센터
Macromolecules, Vol.52, No.24, 9672-9681, 2019
Programmable Thermoresponsive Micelle-Inspired Polymer Ionic Liquids as Molecular Shuttles for Anionic Payloads
To enable the programmable thermoresponsive transport of anions between two phases, multifunctional hyperbranched polymer ionic liquids (hyperPILs) exhibiting micelle-inspired architectures are tailored as molecular shuttles. These polyelectrolytes consist of a hyperbranched poly(3-ethyl-3-hydroxymethyloxetane) (PEHO) core, an inner polyionic imidazolium (Im(+)), and an outer thermoresponsive polyoxazoline (POx) shell, which exhibits lower critical solution temperature (LCST) behavior in aqueous medium. The key step of the hyperPIL synthesis is the efficient chain termination of the cationic ring-opening 2-oxazoline polymerization by the addition of polyfunctional imidazole-terminated PEHO. The resulting covalent attachment of the LCST-POx shell renders hyperPIL polyelectrolytes thermoresponsive. As a function of the polyoxazoline chain length and the oxazoline monomer type, the hyperPIL cloud points (T-CP) vary over a wide temperature range. The inner imidazolium shell enables the immobilization and transport of various anionically charged organic and inorganic payloads via anion exchange. Because of the thermal switching of the hydrophilicity/hydrophobicity balance, hyperPILs function as programmable molecular shuttles for anionic payloads transported back and forth between the phases of ethyl acetate and water. Thus, switchable hyperPILs qualify for manifold potential applications such as catalytic processes with facile recycling of homogeneous catalysts via phase transfer.