Rational Design and Synthesis of Carboxylate Gemini Surfactants with an Excellent Aggregate Behavior for Nano-La2O3 Morphology-Controllable Preparation

Preparation and heat insulation of Gemini-halloysite aerogel/concrete composites

In our previous research, the utilization of Gemini surfactants to control the dispersion and interaction of HNTs aerogels (HCAs) in the concrete matrix had obtained positive research results. In order to further deepen the research in this field, in this work, a Gemini surfactant with a new structure was synthesized, the surface modification characteristics of HCAs in a series of concrete systems were also investigated. Microstructures and properties of the composites were characterized by using scanning electron microscope (SEM), Fourier transform infrared (FTIR), Thermogravimetric analysis (TGA), and so on. The results showed that the newly synthesized Gemini surfactants had an ideal modification effect on the surface of HCAs. Compared with other traditional surfactants, Gemini had better hydrophobic and mechanical properties. Different molecular layers with hydrophilicity or hydrophobicity were constructed on the HCAs surface. The introduction of the modified HCAs could significantly improve the heat insulation performance and mechanical strength of concrete. The improvement of the above comprehensive properties could not have significant difference due to the different types of concrete matrix.

Synthesis and Aggregation Behavior of Jellyfish-Shaped Triazine Hexamer Quaternary Ammonium Chloride Surfactant

A novel jellyfish-shaped triazine hexamer quaternary ammonium chloride surfactant (TH₁₂QC) was synthesized, which consisted of one triazine spacer group and six long flexible hydrophobic chains. The molecular structure and aggregation behavior of TH₁₂QC was investigated by nuclear magnetic resonance (NMR), surface tension, electrical conductivity, dynamic light scattering (DLS), transmission electron microscope (TEM), etc. The results show that the jellyfish-shaped TH₁₂QC has better surface activity and lower surface tension than traditional ionic and Gemini surfactants in aqueous solution. There are two inflection points in the curve of conductivity versus concentration of the TH₁₂QC aqueous solution, which correspond to the critical aggregation concentration (CAC) and the critical micelle concentration (CMC) respectively. The existence of CAC indicates that there is a pre-aggregation process before TH₁₂QC forms micelles. The results of DLS and TEM show that network pre-aggregation, spherical aggregation and dense spherical aggregation were observed in different concentration of TH₁₂QC aqueous solution, and the electrostatic equilibrium of the system subtly depends on the concentration of the solution. In addition, intramolecular and intermolecular hydrogen bonding is also an important factor. This study provides a method for studying the aggregation behavior and morphology of oligomeric surfactants with rigid spacer groups.

A Tetraphenylethene Luminogen-Functionalized Gemini Surfactant for Simple and Controllable Fabrication of Hollow Mesoporous Silica Nanorods with Enhanced Fluorescence

Nanoparticles that possess unique structures and properties are highly desired in the production of multifunctional materials because of their combinational performance. In this study, a facile and effective fabricating strategy is developed to controllably prepare fluorescent hollow mesoporous silica nanorods via the cetyltrimethylammonium bromide (CTAB) and tetraphenylethene (TPE) luminogen-functionalized gemini surfactant (C_TPE-C₆-C_TPE) guided dual-templating approach. Because of its unique chemical structure, water solubility, surface activity, and fluorescent properties, the designed C_TPE-C₆-C_TPE will not only provide an anchored fluorophore for silica nanoparticles but also serve as an intimate partner of CTAB to regulate their construction in the structure-directing process. By properly tuning the molar ratio of CTAB/C_TPE-C₆-C_TPE, the shape-controlled aggregation-induced emission hollow mesoporous silica nanoparticles (AIE-MSNs) can be prepared directly, producing two kinds of silica nanorods (AIE-MSNs-15 and AIE-MSNs-7). In particular, the incorporated bulky TPE luminogens will not only endow AIE-MSNs-7 with enhanced fluorescence intensity (2.3-fold) after the removal of CTAB but also bring about high accessible surface area (606.6 m²/g) and larger pore size (3.2 nm) and pore volume (0.634 cm³/g) for effective loading and sustained release of the hydrophobic anticancer drug camptothecin. C_TPE-C₆-C_TPE enriches the family of gemini surfactants and provides important insights into the convenient fabrication of advanced fluorescent mesoporous materials.

Gemini surfactant with pyrrolidinium head groups and a hydroxyl-substituted spacer: surface properties and assisted one-pot synthesis of dendritic Au nanocrystals

Dendritic Au NCs were facilely prepared by a one-pot method at room temperature with the assistance of gemini surfactant.