The rheological behavior of anionic surfactant sodium oleate (NaOA) in the presence of inorganic salt of sodium carbonate (Na2CO3), organic salt of n-Octyltrimethylammonium bromide (OTAB) and nano-sized silica particles (nano SiO2) was studied in detail. Regardless of the surfactant concentration (NaOA), OTAB was stronger than that of Na2CO3 in promoting the rapid growth of NaOA micelles, resulting in higher viscosity of NaOA aqueous solutions. It was found that nano SiO2 nearly not affects solution viscosity in the NaOA/Na2CO3 system. However, results of NaOA/OTAB system in the presence of nano SiO2 show that nano SiO2 promoted wormlike micelles formation and enhanced the bulk viscosity. Simultaneously, the presence of nano SiO2 also facilitated the branched wormlike micelles formation as confirmed by viscosity and cryo-TEM measurements because of the electrostatic interactions between wormlike micelles and nano SiO2.

A new family of gemini surfactants with pyrrolidinium head groups, 1,1′-(alkane-1, s-diyl)bis(1-dodecyl pyrrolidinium)bromide (C12–Cs–C12PB, s = 3, 4, 6, 8, 10, 12, 14, and 16), were synthesized. Their adsorption and micellization in aqueous solutions were investigated by various techniques such as equilibrium surface tension, fluorescence, and conductivity in detail. It was found that the effect of the spacer length on surfactant aggregation in aqueous solutions is similar to that of the well-known gemini surfactants with quaternary ammonium head groups (m-s-m), whereas the occupied limiting area per molecule (Amin) at the surface increases linearly with s rather than going through a maximum value at a medium value of s like that of m-s-m. The thermodynamic parameters suggest that the micellization of C12–Cs–C12PB is an entropy driven process regardless of the spacer length s. Moreover, a second breakpoint appeared in both γ–log c and I1/I3–c curves of C12–C14–C12PB and C12–C16–C12PB as the surfactant concentration increases, which can be attributed to the formation of larger aggregates. The morphology of the aggregates is confirmed by employing dynamic light scattering (DLS) and cryo-transmission electron microscopy (cryo-TEM) techniques.

A series of pH sensitive single-tailed surfactants, N-alkyl-1,2-ethylenediamine (CmN2N, where m = 8, 10, 12, 14, 16), were synthesized and characterized. The adsorption and aggregation properties of them were determined by equilibrium surface tension, static and dynamic light scattering (SLS and DLS), rheology, and cryogenic transmission electron microscopy (cryo-TEM) techniques in detail. It was found that both the surface activity and self-assembly behavior of CmN2N were strongly dependent on the solution pH, owing to the protonation state of amino groups in CmN2N. When at least one of the amino groups of CmN2N was protonated the logarithm of the critical micelle concentration (cmc) followed the well-known Klevens equation, i.e. cmc decreased linearly with the increase of hydrocarbon chain length. Simultaneously, the surface adsorption area per molecule (Amin) was decreased for each CmN2N when the solution pH varied from acidic to basic conditions. The pH-dependent micelle to vesicle transition was universally observed in the bulk phase of CmN2N. More interestingly, the rodlike micelles formed in C10N2N, C12N2N and C14N2N could transform into vesicles reversibly upon heating or cooling, which indicated the thermal sensitivityof organized assemblies, whereas not in C8N2N and C16N2N.

A series of structurally controllable poly(lauryl methacrylate)-b-poly[N-(2-methacryloylxyethyl)pyrrolidone], PLMA-b-PNMP, diblock copolymers were synthesized by reversible addition–fragmentation chain transfer polymerization. The self-assembly behaviors of PLMA-b-PNMP in a selective solvent, tetrahydrofuran (THF), were studied by employing static light scattering, dynamic light scattering, and transmission electron microscopy in detail. The relationships between the aggregation parameters, such as critical micelle concentration and the aggregation number (Nagg), and the molecular structure were established. It was found that spherical micelles can be formed once the solvophobic block length of poly[N-(2-methacryloylxyethyl)pyrrolidone] is larger than 215. Moreover, extremely small and monodisperse gold nanoparticles (<2 nm) were synthesized by employing PLMA-b-PNMP diblock copolymers in THF.

Trisiloxane surfactants are widely used in pesticide applications as adjuvants to promote spray drop spreading on leaves. The efficacy of the spray is related to the wetting of plant surfaces. The surface (composite or wetted) formed by the liquid drop instantly contacting with the substrate is vital to the spreading. In this paper the spreading behaviors of surfactant solutions on dry and previous wet lotus leaf surfaces were studied. It was found that the drop spreading on the wet surface was obviously easier than on the dry surface, which was rational to the existence of water in the grooves of the wet surface. The spreading of Silwet L-77 aqueous drops on the wet lotus leaf surface is mainly controlled by the surface tension gradient along the air–liquid interface.Water modified wetting behavior on lotus leaf. It is clear that entrapped water has a significant effect on lotus wetting behavior.