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A new lubricating coating with functionalized graphene oxide (fGO) consisting of graphene oxide (GO) with different oxidation degrees, n-octylamine basal plane functionalized GO (bGO), and edge functionalized GO (eGO) was developed with or without 3-aminopropyltrimethoxysilane (APTMS) to reduce friction in macroscale contact with water. The optimal preparation condition of the coating was obtained by the single factor evaluation of a series of factors (20 % APTMS aqueous solution, 12 h immersion time, 0.05 mg/mL GO aqueous solution, and 100 °C curing temperature). The effect of the oxidation degree and functionalization of GO on the friction-reducing and anti-wear behavior of the coating was explored. The coatings with a higher GO oxidation degree exhibited better friction-reduction and anti-wear performance. In addition, the friction-reducing capability of the APTMS-bGO coating was greater than that of APTMS-eGO.

In this work, four types of comb-like dispersants and one linear dispersant were synthesized to explore the effect of dispersant structure on the bubble structure in water solution and mortar system for the first time. Dispersants were modified with different adsorption groups (i.e., carboxylic acid, phosphate ester, and sulfonic groups). Polymer structures were identified using gel permeation chromatography and infrared spectroscopy. Surface tension test indicated that the comb-like dispersants exhibited lower surface tension than that of the linear dispersants (NSF-2), thereby demonstrating that the polycarboxylate superplasticizer (PCE) solutions possessed high surface activity. The analysis of the foamability and foam stability of the comb-like and linear dispersants were comprehensively investigated at different concentrations. Comb-like dispersants possessed higher foam height and better foamability performance than those of the linear dispersants. The bubbles of the dispersant PCE-3 were smaller in terms of the mean area and possessed higher number of bubbles than those of the other dispersants, which may be essential in reducing the viscosity of the slurry. A similar result was also obtained in the mortar system tested using the AVA instrument for PCE-3 and NSF-2. Adsorption and rheological behavior test indicated that comb-like dispersant PCE-3 is the most effective in reducing the viscosity of the slurry among all the dispersants tested. This result is consistent with that of the foamability experiment.

Photo-responsive materials with adjustable self-assembly morphologies and tunable rheological properties have attracted widespread interests of researchers in recent years because of their potential applications in controlled release, microfluidics, sensors, and so forth. In this paper, a series of UV-sensitive anisotropic fluids were prepared by combining trans-ortho-methoxycinnamate (trans-OMCA, in its salts form) and cationic Gemini surfactant propanediyl-α, ω-bis (N-dodecyl-N, N-dimethylammonium bromide) (12-3-12·2Br−) based on the research of self-assembly behaviors of the mixed system. The photo-responsive behaviors of anisotropic fluid formed in 12-3-12·2Br−/trans-OMCA/H2O system including macroscopic phase transition, microstructure transformation, rheological property, molecular interaction and isomerization degree of trans-OMCA were investigated by various techniques including UV-vis spectrum, rheology measurement, 1H NMR and 2D NOESY spectrum, transmission electron microscopy (TEM), polarized optical microscopy (POM), and dynamic light scattering (DLS). It is proved that upon exposure to UV-light, ortho-methoxycinnamate (OMCA) undergoes a photo-isomerization from trans form to cis form, which results in geometry transitions of the 12-3-12·2Br−/OMCA aggregates accompanied by a continuous phase separation and combination macroscopically; both proportion and concentration of OMCA in anisotropic solution have great influences on the photo-responsive behaviors of the system including the durations of UV irradiation and isomerization degrees of OMCA at the phase transition points. The photo-responsiveness of this smart fluids and the quantitative analysis are expected to provide reference for academic research or practical application in the fields of biomedicine, soft matters, food engineering and sunscreen.

The structure and number of air-voids in concrete can greatly affect the macroscopic performance of concrete. Therefore, the development of highly efficient concrete air content regulators, such as air-entraining agents or defoamers, is important. In this work, one novel block phenyloxy polyether with different propylene oxide (PO) units was successfully synthesized, and this kind of surfactants could be used as air-entraining agents or defoamers by controlling the ratio and position of PO in the polymer structure. The structures of these surfactants were verified by 1H NMR and infrared spectroscopy. Results of foamability and foam stability tests of these surfactants in water solutions indicated that the position and ratios of PO in the polymer structure have a remarkable effect on the foam properties of the surfactants. When these surfactants were applied to cement mortar, surfactant S4 with PO units adjacent to benzene ring group exhibited excellent air entrainment performance, whereas surfactants S8 and S9 with PO units at the end of the polymer showed obvious defoaming ability. The surface activity, adsorption and rheological properties were also tested to understand this type of surfactants. The results of concrete application and mechanism study showed that this type of surfactant had great potential for practical application.

A new phase separation system, aqueous multiphase system (MuPSs, ranging from two to four phases), containing surfactants and polymer (SDS/DTAB/PEG/NaBr/H 2 O) was designed and the complicated four-phase systems were investigated systematically. To interpret the phase separation phenomena, the phase composition, phase density, phase volume ratio between the studied phase and the whole system as well as the particle size and zeta potential of aggregates in each phases were investigated. The results have shown that the multiphase system contains liquid crystal phase, which may imply a close relationship between MuPSs and liquid crystal. At the same time, it seems there is a direct relationship between zeta potential of the existed phase and the appearance of new phase. Phase composition analysis results illustrate that the rich component for the three phases from top to the third one are PEG, DTAB, and SDS, respectively. However, the bottom phase is almost dilute brine. Furthermore, the differential scanning calorimetry experiments prove that the micro-complexity of aggregates in different phases is different from each other. The studied MuPSs are very stable but temperature sensitive; the coexisted phases have different extraction power to xylenol orange because of the variation of composition. The higher stability of MuPSs makes it useful when the storage and long-term stability of the separation media are important. The work not only provides theoretical guidance for the development of efficient extraction and separation technology but also provides new opportunities for the development of aqueous multiphase systems.

Dielectric materials with ultralow dielectric constants (

The middle-phase microemulsion (Winsor III) induced by salt in the low surfactant + cosurfactant (S + A) region of n -butanol/ n -octane/water/alkanediyl-α,ω(dimethydodecyl-ammonium bromide) (12-3-12) system was investigated by salinity scan. It is shown that the original water-in-oil single phase cannot form Winsor III even when the NaCl aqueous solution added reaches saturation. However, the original coexisting multi-phase and oil-in-water single phase can form Winsor III easily in a wide concentration range of salt, which is favorable to the application of Winsor III. The super low salinity for the initial formation of Winsor III ( S 1 ) attributes to the special structure of geminis. The water content, salinity, and temperature have great effect on the volume fraction of Winsor III and the temperature induces different phase transition from Winsor II to Winsor III. The condition for the formation of stable Winsor III was obtained by the interfacial tension (IFT) measurements. The multi-phase microemulsion was also studied by fluorescence, and the information, which was used to determine the microstructure of single-phase microemulsion. The results agree well with that obtained from the conductivity measurement carried out in our previous work.

Salts NaCl, KCl or NaBr shorten the phase-separation time of the ATPS (aqueous two-phase system) in mixed solutions of Gemini (12-3-12,2Br − ) and sodium dodecyl sulfate (SDS). They also change the region of ATPS; it moves toward higher molar mixing ratios of Gemini to SDS and becomes wider. The minimum concentration of surfactant needed for the formation of ATPS is also lowered. Negative ions play the dominant role. Densities of the coexisting phases are strongly influenced by the total concentration of surfactants, the molar mixing ratio of Gemini to SDS, temperature and the type of salt. For some cases, phase inversion (the upper phase changes to lower and the bottom phase changes to upper) appears. Salts notably enhance extraction ability; the oil-like phase (looks like oil in appearance), a Gemini-rich solution, shows affinity for xylenol orange. Results obtained from negative-staining and transmission electron microscopies show that salts change the microstructures of the two phases. In the oil-like phase, the long rod-like micelles tend to congregate into big-rammed aggregates and form a coarse network structure that increases viscosity. The conjugate phase contains mixed multilamellar vesicles, micelles, loops and cylindrical micelles.

Phase behavior and microstructures have been investigated for aqueous mixtures of cationic Gemini surfactant (12-3-12,2Br−) and anionic surfactant sodium dodecyl sulfate (SDS) using freeze-etching and negative-staining and with transmission electron microscopy (TEM). The phase diagram shows different regions characterized by different microstructures. Most of the regions are occupied by multi-lamellar phases in which vesicles coexist with micelles when the solutions are dilute. The multi-lamellar vesicles have higher stability because of their special structures. The ratio of vesicles to micelles varies with concentration and composition of the mixed-surfactant solutions. At higher surfactant concentrations, we observe other phases: the lamellar phase, anisotropic phase, aqueous two-phase system (ATPS), rod-like micelle phase, as well as other unique microstructures such as cylindrical micelles formed by short rod-like micelles, and porous morphology. Observations are reported for the transformation among different phases, especially from rod-like to spherical micelles.