Synthesis and Aggregation Behavior of Trisiloxane Ionic Liquids in Aqueous Solution. Issue 4 (16th May 2019) - Tan, Jinglin
Abstract: Trisiloxane ionic liquids with polyether groups (Si3 pyCl‐EO3 ) were synthesized via thiol‐ene reaction between 1‐methyl‐1‐[bis(vinyldimethylsiloxy)methyl]silylpropylpyrrolidinium chloride (Vi‐Si3 pyCl) and tri(ethylene glycol) methyl ether thiol. The aggregation behavior of the trisiloxane ionic liquids, Si3 pyCl‐EO3 and Vi‐Si3 pyCl, in aqueous solution was investigated using surface tension, electrical conductivity, dynamic light scattering, and transmission electron microscopy. The structures of trisiloxane ionic liquids can obviously influence their aggregation behavior. Vi‐Si3 pyCl has excellent surface activity (22.3 mN m −1 ). However, Si3 pyCl‐EO3 can only reduce the surface tension of water to 33.5 mN m −1 . In comparison with Vi‐Si3 PyCl, Si3 PyCl‐EO3 has a bulkier hydrophobic group and a higher Α min value (127.8 Å 2 ) caused by the introduction of the tri(ethylene glycol) methyl ether groups by thiol‐ene reaction. The micellization of Vi‐Si3 PyCl is entropy driven, while the aggregation process of Si3 PyCl‐EO3 in aqueous solution is enthalpy driven.