Thermoresponsive homo-polymeric ionic liquid as molecular transporters via tailoring interchain pi-pi interactions and its unique temp-resistance behavior during ions pairing

In this study, a polymeric ionic liquid (PIL) called Poly[ECH-BIM]Cl was polymerized by ring-opening and quaternization reaction of benzimidazole and epichlorohydrin without additional ion-exchange reaction. Both 1H NMR and fourier transform infrared (FTIR) confirmed the chemical structure of Poly[ECH-BIM]Cl. Poly[ECH-BIM]Cl in water was thermoresponsive and its UCST transition was studied by UV-vis spectrometry, dynamic light scattering (DLS) and scanning electron microscopy (SEM) at variable temperature. Moreover, the first introduced Temp-resistance behavior during ions pairing found Poly[ECH-BIM]Cl had properties similar to those of the precipitation of inorganic salts from their saturated solutions. The variable-temperature 1H NMR analysis demonstrated that the tailored interchain pi-pi interactions promoted the aggregation of macromolecular chains and particles formed from Poly[ECH-BIM]Cl aqueous solution. The results showed that increasing the interaction between cations of PIL can endow its thermosensibility and the possibility of being a programmable shuttle.