Synthesis of thermoresponsive polysilsesquioxane with methoxyethylamide group and crown ether

Abstract

A polysilsesquioxane with a bis(2-methoxyethyl)amide group and 15-crown-5-ether ring (MCPSQ) was newly prepared by the co-condensation of silane coupling reagents, which were obtained from (3-isocyanatopropyl)triethoxysilane and the corresponding amines with the respective groups. MCPSQ showed the expected amphiphilic and thermoresponsive properties. The behaviors of hydrophobic aggregation of MCPSQ in the aqueous solutions containing the chlorides of lithium, potassium and sodium reflected the selective ion recognition property due to the presence of the crown ether. The highest aggregation temperature of 32 1C was observed in the solution containing sodium ion as expected from the coordination ability of the crown ether group. With the use of the sodium salt of 4-phenylazobenzoic acid as an additive in the aqueous solution of MCPSQ, the aggregation temperature was changed according to the photochemical isomerization of the phenylazobenzoate group. The results show the efficient coordination of the sodium salt with the crown ether ring.

Supramolecular control over thermo‐responsive systems with lower critical solution temperature behavior

“…Moreover, the crown ether‐appended LCST systems were sensitive to cations, but relatively insensitive to anion species. [ 46 ]…”