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Preparation of POSS-min-DS, an octaimidazolium-based polyhedral oligomeric silsesquioxanes (POSS) room temperature ionic liquid, by an ion-exchange reaction between POSS and sodium dodecyl sulfate was reported. Octaimidazolium-based POSS was synthesized with more than 98% yield within 3 h. POSS-min-DS and octaimidazolium-based POSS were confirmed by (1)H, (13)C, and (29)Si NMR, FT-IR and elemental analysis.

A series of polyether based siloxane surfactants with different branched chain and alkyl groups were synthesized by thiol−ene reaction and Piers−Rubinsztajn reaction. The effect of the siloxane structures (alkyl groups and branched chains) on the adsorption and aggregation behavior in aqueous solution was investigated by surface tension, fluorescence, dynamic light scattering (DLS), freeze-fracture transmission electron microscopy (TEM), and TEM. The molecular structures of siloxane can obviously influence their surface activities and thermodynamics. Replacing the methyl of trimethylsiloxyl groups with longer alkyl groups (ethyl, propyl, and butyl) and branching trimethylsiloxyl resulted in an obvious decrease of the values of critical micelle concentration (CMC) and surface tension at CMC (γ CMC ). Dense surface films packed with CH 3 groups result in the lower surface tensions being disordered by longer alkyl groups or branched chains of siloxane hydrophobic groups. And the minimum surface area per surfactant molecule (A min ) values of Si 3 -PG, Et-Si 3 -PG, Pro-Si 3 -PG, and But-Si 3 -PG successively decrease about 3.5 Å with each increasing −CH 2 − group. All polyether based siloxane surfactants can form nonuniform size spheroidal aggregates in aqueous solution. Concerning the driving force, the micellization process was spontaneous but less spontaneous compared with adsorption.

The micellization of two silicone ionic liquids, 1-methyl-1-[tri-(trimethylsiloxy)]-silylpropylpyrrolidinium nitrate (Si 4 pyNO 3 ) and 1-methyl-1-[tri(trimethylsiloxy)]-silylpropylpyrrolidinium acetate (Si 4 pyAc), with different counterions was systematically investigated by surface tension and electrical conductivity. Surface tension of water can be reduced almost to 20 mN·m −1 with the addition of the silicone ionic liquids, indicating that the silicone ionic liquids exhibit excellent surface activity. The critical micelle concentration (CMC) values of Si 4 pyNO 3 are less than those of Si 4 pyAc. Electrical conductivity measurements show that the degree of counterion binding (β) for Si 4 pyNO 3 is twice as large as that for Si 4 pyAc. Thermodynamic parameters (ΔH m 0 , ΔS m 0 , and ΔG m 0 ) of micellization derived from electrical conductivities indicate that the micellization for both Si 4 pyNO 3 and Si 4 pyAc is enthalpy-driven process. The heat capacities, Δc m,p 0 , are negative for the two silicone ionic liquids relating to the removal of water accessible nonpolar surfaces. The addition of sodium halides in the aqueous solution decreases CMC remarkably; however, the surface tension at CMC stays the same with the salt-free system. ■ INTRODUCTIONIonic liquids (ILs) are increasingly gaining interest as a class of environmentally friendly solvents due to their unique properties, such as nonvolatility, nonflammability, and high ionic conductivity. 1−3 To date, ILs based on pyrrolidinium, pyridinium, imidazolium, and quaternary ammonium cations with a variety of anions, such as halides, PF 6 − , NO 3 − , BF 4 − , CH 3 COO − , and CF 3 SO 3 − , have been successively synthesized and widely utilized in separation, organic synthesis, fuel cell, catalysis, and preparation of nanomaterials. 4−9 Specially, in recent years, hydrocarbon ILs, such as 1-methyl-3-alkylimidazolium ILs, have been extensively studied as novel surfactants, and much research on their aggregation behavior in aqueous solution has been reported. 10−13 In addition, more research has focused on the effect of structural change (especially the long hydrocarbon chain and cationic structure) on the aggregation behavior of ILs in aqueous solution. 14−20 Meanwhile, silyl and siloxy substituted imidazolium ILs have been reported. 21−23 Then, aggregation behavior of trisiloxane-tailed ionic liquids in aqueous solution has also been investigated. 24 Owing to the excellent properties of silicone surfactants, such as excellent surface activity, low toxicity, and outstanding association behavior, silicone surfactants have been widely used in the field of colloid and interface science. 25−31 The interfacial behaviors of silicone surfactants were strongly influenced by the number of silicon atoms and demonstrated that the siloxane portion oriented at the water surface with an "umbrella" conformation. 31 Moreover, the entire hydrophobic effect of the silicone surfactants is due to CH 3 and CH 2 groups coupled to siloxane chain and the Si−O units are neither hyd...

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