Green and environmentally friendly ionogels formed by a sugar surfactant were prepared in two kinds of imidazolium-based ionic liquids. The phase transition from ribbon structures to lamellar structures induced by temperature and the transition mechanism were investigated in detail by means of freeze-fracture TEM and field-emission SEM observations, as well as small-angle X-ray scattering measurements. The rheological properties and tribological properties of two kinds of ionogels were systematically investigated. The difference in the lubricating properties and antiwear capability can be explained well by the mechanical and viscoelastic properties, as well as the different microstructures of samples destroyed by shear forces. This work provides a better understanding of the relationship between the structures, rheological properties, and tribological properties of ionogels.

The aggregation behavior of mixtures of the alkaline amino acid L-Arginine (L-Arg) and bis(2-ethylhexyl)phosphoric acid (DEHPA) in water was studied in detail. At a fixed L-Arg concentration, a phase sequence of micellar phase (L₁ phase), vesicle phase (L_αv phase), planar lamellar phase (L_αl phase), and sponge phase (L₃ phase) was obtained with increasing DEHPA concentration due to changes in the packing parameter. The phase transition of the lamellar structures was determined by freeze-fracture TEM and ²H NMR spectroscopy. Rheological measurements reflected the phase transition through significant variations of both the elastic modulus and the viscous modulus. Porous CeO₂ materials were produced by utilizing the L₃ phase as template, and the porous CeO₂ exhibited excellent catalytic oxidation activity toward CO due to its high surface area, which provides more active sites for CO conversion.

Self-assembly regulated by hydrogen bonds was successfully achieved in the system of lithocholic acid (LCA) mixed with three organic amines, ethanolamine (EA), diethanolamine (DEA), and triethanolamine (TEA), in aqueous solutions. The mixtures of DEA/LCA exhibit supergelation capability and the hydrogels consist of plenty of network nanotubes with uniform diameters of about 60 nm determined by cryogenic TEM. Interestingly, the sample with the same concentration in a system of EA and LCA is a birefringent solution, in which spherical vesicles and can be transformed into nanotubes as the amount of LCA increases. The formation of hydrogels could be driven by the delicate balance of diverse noncovalent interactions, including electrostatic interactions, hydrophobic interactions, steric effects, van der Waals forces, and mainly hydrogen bonds. The mechanism of self-assembly from spherical bilayer vesicles into nanotubes was proposed. The dried hydrogels with nanotubes were explored to exhibit the excellent capability for capturing heavy-metal ions, for example, Cu²⁺, Co²⁺, Ni²⁺, Pb²⁺, and Hg²⁺. The superhydrogels of nanotubes from the self-assembly of low-molecular-weight gelators mainly regulated by hydrogen bonds used for the removal of heavy-metal ions is simple, green, and high efficiency, and provide a strategic approach to removing heavy-metal ions from industrial sewage.

The surface and bulk properties of aqueous mixtures of nonionic tetraethylene glycol monododecyl ether (C₁₂EO₄) and anionic perfluorolauric acid (PFLA) were studied. These mixtures exhibited pronounced synergistic effects in terms of their mixed micellization and rheological properties. Only one type of mixed micelle is formed in dilute mixed solutions. At low PFLA content, with increasing the total surfactant concentration, short thread-like micelles grow to form larger discs. On increasing the amount of PFLA, owing to the fact that the fluctuant planar bilayers of nonionic C₁₂EO₄ become charged, vesicle gels that are comprised of densely packed unilamellar and multilamellar vesicles spontaneously form, in which the fluorocarbon chains in the bilayers are in a fluid state at room temperature. The elastic properties and the yield stress of the lamellar solutions largely increase upon the addition of small amounts of PFLA and they then pass through a maximum at a saturation of effective membrane charge density. Interestingly, increasing the pH value of the gels causes a backward transition from stiff vesicles to flexible planar bilayers. On increasing the amount of NaOH, the bilayers exhibit greater flexibility, owing to the decrease in membrane charges, along with a large decrease in the solution viscosity and their elastic properties. The combination of strong stability of the vesicle gels with the interconvertible transition of bilayers and vesicles is expected to be of practical use for controlled drug delivery and release.

Viscoelastic vesicle gels were prepared by mixing a nonionic surfactant, tetraethylene glycol monododecyl ether (C₁₂EO₄), and an anionic dye, sodium 4-phenylazobenzoic acid (AzoNa). The gels, which were composed of multilamellar vesicles, were analyzed by cryogenic transmission electron microscopy (cryo-TEM), freeze–fracture transmission electron microscopy (FF-TEM), ²H NMR spectroscopy, and small-angle X-ray scattering (SAXS). The mechanism of vesicle-gel formation is explained by the influence of anionic molecules on the bilayer bending modulus. Interestingly, the vesicle gels were observed to be sensitive to temperature, pH, and light. The viscoelastic vesicle gels respond to heat; they thin at lower temperatures and become thicker at higher temperatures. The vesicle gels are only stable from pH 7 to 11, and the gels become thinner outside of this range. UV light can also trigger a structural phase transition from micelles to multilamellar vesicle gels.

We report a new, simple strategy to apply honeycomb films for the patterning of colloidal particles. By combination of a “bottom-up” breath figure method and the electrochemical properties of the honeycomb films of ferrocenyl-based oligomers, highly ordered hybrid membranes coated with ring-like patterning of 0D- and 1D-Ag nanoparticles (NPs) have been fabricated. One interesting phenomenon is that the nucleation and adsorption of Ag dots occurred preferentially at the edges of the micropores. The hybrid membranes exhibited richly electrochemical activities towards reduction of iodate and enhanced effectively catalytic reduction of organic dyes. We believe that this method can be used to decorate and/or assemble functional metal NPs such as Au, Pd, and Cu on honeycomb-patterned materials for the further applications of photonics, sensors, and catalysis.

Ferrum laurate [Fe(OOCC₁₁H₂₃)₃] metallosurfactant can successfully self-assemble into reversed vesicles in organic media such as pure CHCl₃ and a mixed solvent of CHCl₃ and CH₃OH. Deformed solid vesicles, including collapsed erythrocyte-like and broken hollow shells, were obtained directly by slectively drying the organic solvents. The morphology of the reversed vesicles of metallosurfactant in the organic media to hardly solid shells is maintained and it is ascribed to the evaporation rate of the solvents and the interactions between ferrum laurate and solvents.

Under acidic conditions, reduced graphene oxide (rGO) was functionalized with p-aminobenzoic acid, which formed the diazonium ions through the diazotization with a wet-chemical method. Surfactants or stabilizers were not applied during the diazotization. After the functionalized rGO was treated through mild sonication in aqueous solution, these functionalized rGO sheets were less than two layers, which was determined by atomic force microscopy (AFM) imaging. The water solubility of functionalized rGO after the introduction of polyethyleneimine (PEI) was improved significantly; it was followed by covalent binding of folic acid (FA) molecules to the functionalized rGO to allow us to specifically target CBRH7919 cancer cells by using FA as a receptor. The loading and release behaviors of elsinochrome A (EA) and doxorubicin (DOX) on the functionalized rGO sheets were investigated. The EA loading ratio onto rGO-C₆H₄-CO-NH-PEI-NH-CO-FA (abbreviated rGO-PEI-FA, the weight ratio of drug loaded onto rGO-PEI-FA) was approximately 45.56 %, and that of DOX was approximately 28.62 %. It was interesting that the drug release from rGO-PEI-FA was pH- and salt-dependent. The results of cytotoxicity (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and flow cytometry (FCM) assays, as well as cell morphology observations) clearly showed that the concentration of rGO-PEI-FA as the drug-delivery composite should be less than 12.5 mg L⁻¹. The conjugation of DOX and rGO-PEI-FA can enhance the cancer-cell apoptosis effectively and can also push the cancer cells to the vulnerable G2 phase of the cell cycle, which is most sensitive and susceptible to damage by drugs or radiation.

Inverse opal films with unique optical properties have potential as photonic crystal materials and have stimulated wide interest in recent years. Herein, iridescent hybrid polystyrene/nanoparticle macroporous films have been prepared by using the breath-figure method. The honeycomb-patterned thin films were prepared by casting gold nanoparticle-doped polystyrene solutions in chloroform at high relative humidity. Highly ordered hexagonal arrays of monodisperse pores with an average diameter of 880 nm are obtained. To account for the observed features, a microscopic phase separation of gold nanoparticles is proposed to occur in the breath-figure formation. That is, individual gold nanoparticles adsorb at the solution/water interface and effectively stabilize condensed water droplets on the solution surface in a hexagonal array. Alternatively, at high nanoparticle concentrations the combination of breath-figure formation and nanoparticle phase separation leads to hierarchical structures with spherical aggregates under a honeycomb monolayer. The films show large features in both the visible and NIR regions that are attributed to a combination of nanoparticle and ordered-array absorptions. Organic ligand-stabilized CdSe/CdS quantum dots or Fe₃O₄ nanoparticles may be loaded into the honeycomb structure to further modify the films. These results demonstrate new methods for the fabrication and functionalization of inverse opal films with potential applications in photonic and microelectronic materials.

Honeycomb-patterned polymer films with tunable pore size and regularity of ordered two- or three-dimensional hexagonal arrays have met with widespread interest in recent years in different areas, for instance as separation and superhydrophobic materials. Herein, 2D honeycomb-patterned films of amphiphilic ferrocenyl-based oligomer with cholesterol as side chains were prepared by the breath-figure method on solid surfaces and their surface-wetting behavior were tested. These films can be simply prepared by spreading a mixture of polymer and organic solvents on a solid surface under moist airflow and at an air/water interface without any extra moist airflow. An ordered 2D hexagonal array of pores with monodisperse size distribution can be obtained over a large area by changing various influencing factors, including humidity, wet volume, concentration, selective solvent, and spreading method, which provides a facile route to regulate the morphology of patterned porous films. The surface-wetting behavior indicates that a higher hydrophobicity of the ferrocenyl-based oligomer honeycomb films can be obtained by modulating the pore size and regularity. It is expected that this could promote the potential application of ordered porous polymer films in hydrophobic materials and biochemistry.

The breath figure method was used to prepare dodecanethiol-capped gold nanoparticle macroporous structures with pore diameters from 1.7 to 3.5 μm on an air/water interface. A two-step procedure is proposed for the fabrication of these macroporous structures, by forming a surfactant monolayer on water, and drop-casting a gold nanoparticle dispersion in chloroform onto the surfactant monolayer. The self-assembled films are easily transferred from the water surface onto different substrates and were characterized by TEM, SEM, and AFM. Ordered honeycomb structures with different pore arrays (perforated monolayer films, hexagonal networks and alveoli-like porous films) were obtained. The change in morphology is concentration dependent, and deformed structures with elliptic honeycomb networks are also observed. In addition, honeycomb films using gold nanoparticles stabilized by a weakly bound ligand (dioctadecyldimethylammonium chloride) were formed by the same technique. These films have potential as substrates for surface-enhanced Raman spectroscopy.

Polymer-grafted multiwalled carbon nanotube (MWCNT) hybrid composite which possess a hard backbone of MWCNT and a soft shell of brush-like polystyrene (PSt) were synthesized. The reversible addition fragmentation chain transfer (RAFT) agents were successfully immobilized onto the surface of MWCNT first, and PSt chains were subsequently grafted from sidewall of MWCNT via RAFT polymerization. Chemical structure of resulting product and the quantities of grafted polymer were determined by Fourier transform infrared, thermal gravimetric analysis, nuclear magnetic resonance, and X-ray photoelectron spectra. Transmission electron microscopy and field emission scanning electron microscopy images clearly indicate that the nanotubes were coated with a polymer layer. Furthermore, the functionalized MWCNT as additives was added to base lubricant and the tribological property of resultant MWCNT lubricant was investigated with four-ball machines. The results indicate that the functionalization led to an improvement in the dispersion of MWCNT and as additives it amended the tribological property of base lubricant. The mechanism of the significant improvements on the tribological properties of the functionalized MWCNT as additives was discussed. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 3014–3023, 2008

A novel polyelectrolyte-grafted multiwalled carbon nanotubes (MWCNTs-g-PILs) which possesses a hard backbone of MWCNTs and a soft shell of brush-like poly (ionic liquids) (PILs) has been synthesized via the surface atom transfer radical polymerization (ATRP). Chemical structure and the grafted PILs quantities of MWCNTs-g-PILs were determined by FTIR, TGA, and XPS. TEM and FE-SEM observations indicate that the nanotubes were coated with a PILs layer, exhibiting core-shell nanostructures with the PILs chains as the brush-like or hairy shell and the MWCNTs as the hard backbone. Furthermore, the effect of counter-anions on the solubility of MWCNTs-g-PILs was investigated. The results indicate that relative solubility of MWCNTs-g-PILs in various solvents could be switched by anion exchange. This tunable solubility results in the formation of the cycle of reversible phase-transition. Tribological property of MWCNTs-g-PILs as additives in base lubricant 1-methyl-3-butylimidaaolium hexafluorophosphate (LP104) was evaluated using an Optimol SRV oscillating friction and wear tester, confirming that MWCNTs-g-PILs are the excellent antiwear and friction-reducing additives, which can amend the tribological properties of base lubricant significantly. This is attributed to the good dispersibility and core-shell structure of MWCNTs-g-PILs. These results reported in this work may open primarily toward constructing a bridge among carbon nanotues (CNTs), ILs, and lubricant additives and secondarily to prove that CNTs (modified CNTs) as lubricant additives are promising candidates. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7225–7237, 2008