Surfactant oligomers are made up of x (≥2) amphiphilic moieties connected at the level of, or close to, headgroups by spacer group(s). This paper examines effect degree oligomerization on self-assembling cationic surfactant interfaces and in bulk. The quaternary ammonium bromide investigated dodecyldimethyl- dodecylmethylammonium short polymethylene spacers −(CH2)s− (of carbon number s). properties surface occupied air/solution silica/solution interfaces, critical micellization concentration...

The microviscosity of micelles the dimeric (gemini) surfactants alkanediyl-α,ω-bis(dimethyldodecylammonium bromide), referred to as 12-s-12 (s = carbon number alkanediyl spacer), has been obtained from measurements fluorescence anisotropy micelle-solubilized diphenylhexatriene (DPH) and intensity ratio IM/IE dipyrenylpropane (P3P, IM IE intensities monomer excimer emissions). micropolarity these surfactant was characterized by value I1/I3 first third vibronic peaks in emission spectra...

We have investigated the active motion of self-propelled colloids confined at air-water interface and explored possibility enhancing directional Janus by slowing down their rotational diffusion. The two dimensional micron-sized silica-platinum has been experimentally measured particle tracking video-microscopy increasing concentrations catalytic fuel, i.e. H2O2. Compared to in bulk, a dramatic enhancement both persistence length trajectories speed observed. interplay colloid self-propulsion,...

Interfacial tension, electrical conductivity, NMR self-diffusion and DLS experiments have been used to investigate the self-aggregation in water of ionic liquids associating an ibuprofenate anion 1-alkyl-3-methylimidazolium [CnMIm]+ (n = 4, 6, 8) cations. Despite short alkyl chain on imidazolium cations ≤ 8), these exhibit particularly low Critical Aggregation Concentrations (CAC), significantly lower than their parent chloride salts. This behaviour is attributed formation catanionic pairs...

Aggregates formed in an aqueous medium by three ionic liquids CnMImIbu made up of 1-alkyl-3-methyl-imidazolium cation (n = 4, 6, 8) and ibuprofenate anion are investigated. Dynamic light scattering (DLS), cryogenic transmission electron microscopy (cryo-TEM), (1)H nuclear magnetic resonance measurements, atom-scale molecular dynamics simulations used to shed on the main interactions governing formation aggregates their composition. At high concentration, mixed micelles with a composition...

Biological or artificial microswimmers move performing trajectories of different kinds such as rectilinear, circular, spiral ones. Here, we report on circular observed for active Janus colloids trapped at the air–water interface. Circular motion is due to asymmetric and nonuniform surface properties particles caused by fabrication. Motion persistence enhanced partial wetted state actively moving in two dimensions The slowing down in-plane out-of-plane rotational diffusions described discussed.

Formation of a dominant population closed loops in wormlike micellar systems, theoretically predicted but never reported so far, is achieved with new cationic surfactant tetramer. The contour length distribution N(L) the closed-looped micelles determined by transmission electron microscopy at cryogenic temperature. At large lengths, observed scales as ∝ L-5/2, expected from ring−chain equilibrium polymerization theory. small rigidity-dependent ring closure probability provides direct...

We examine the behavior of spherical silica particles trapped at an air–nematic liquid crystal interface. When a strong normal anchoring is imposed, beads spontaneously form various structures depending on their area density and nematic thickness. Using optical tweezers, we determine pair potential explain formation these patterns. The energy profile discussed in terms capillary elastic interactions. Finally, detail mechanisms that control hexagonal lattice analyze role gravity for curved interfaces.

Hybrid polyion complex (HPIC) micelles are nanoaggregates obtained by complexation of multivalent metal ions double hydrophilic block copolymers (DHBC). Solutions DHBC such as the poly(acrylic acid)-block-poly(acrylamide) (PAA-b-PAM) or acid)-block-poly(2-hydroxyethylacrylate) (PAA-b-PHEA), constituted an ionizable complexing and a neutral stabilizing block, were mixed with solutions ions, which either monoatomic polycations, Al3+, La3+, Al137+. The physicochemical properties HPIC...

We report theoretical predictions and measurements of the capillary force acting on a spherical colloid smaller than length that is placed curved fluid interface arbitrary shape. By coupling direct imaging interferometry, we are able to measure in situ contact angle correlate its position with respect curvature. Extremely tiny forces down femtonewtons can be measured this method. Measurements agree well theory relating gradient Gaussian curvature mean prior colloidal deposition. Numerical...

Self-assembling peptides (SAPs) have been extensively studied for their ability to form nanoscale ordered structures driven by noncovalent molecular interactions. Meanwhile, polymerization-induced self-assembly (PISA) has exploited as a facile and efficient way produce various amphiphilic block copolymer nano-objects, whose was governed predominantly the interactions of different blocks with polymerization medium. In this work, we combined PISA SAPs prepare novel peptide–polymer hybrid thus...

Gemini surfactants are made up of two surfactant‐like moieties connected by a spacer group. This article reviews their phase behavior, considering successively the thermotropism pure gemini surfactants, lyotropism in surfactant/water mixtures, and ability to give rise microemulsions presence oil water (and eventually cosurfactant). From qualitative viewpoint have been found behave similarly corresponding monomeric as far behavior is concerned. However, reported results indicate that length...

Janus colloidal particles show remarkable properties in terms of surface activity, self-assembly and wetting. Moreover they can perform autonomous motion if chemically react with the liquid which are immersed. In order to understand self-propelled catalytic colloids at air–water interface, wetting orientation important be investigated. Wetting plays a central role active since it determines contact between fuel as well efficiency transduction chemical reaction into motion. Active is not...

A mild and simple way to prepare stable aqueous colloidal suspensions of composite particles made a cellulosic material (Sigmacell cellulose) multiwalled carbon nanotubes (MWCNTs) is reported. These can be dried redispersed in water at pH 10.5. Starting with rather crude initial materials, commercial Sigmacell cellulose MWCNTs, significant fraction dispersed could obtained. The solid composites their were characterized by electronic microscopy, thermal analyses, FTIR Raman spectroscopy,...

The adsorption of a sunflower protein extract at two air–water and oil–water interfaces is investigated using tensiometry, dilational viscoelasticity, ellipsometry. For both interfaces, three step mechanism was evidenced thanks to master curve representations the data taken different aging times concentrations. At short times, diffusion limited proteins demonstrated. First, two-dimensional film formed with partition polypeptide chains in phases that depends strongly on nature hydrophobic...

The rheological behavior of a cationic surfactant trimer, recently suggested to form branched threadlike micelles, is reported. Comparison with the homologous dimer, which forms strictly linear shows that main consequence branching distinctive concentration dependence elastic modulus. When system not fully entangled, decrease modulus suggests contraction radius gyration due branching. In entangled regime, elasticity enhancement provides measure junction density.

Reduce, reuse, recycle: A new methodology allows the synthesis of ordered mesoporous materials in water at room temperature, eliminating need for organic solvents and reducing amount energy consumed. It relies on reversible formation micelles water-soluble block copolymers as structure-directing agents (see picture). After recovery material, reaction solution can be used again. Detailed facts importance to specialist readers are published ”Supporting Information”. Such documents...

Using aminoglycoside antibiotics as drug models, it was shown that electrostatic complexes between hydrophilic drugs and oppositely charged double-hydrophilic block copolymers can form ordered mesophases. This phase behavior evidenced by using poly(acrylic acid)-block-poly(ethylene oxide) in the presence of silica precursors, this allowed preparing drug-loaded mesoporous directly from drug-polymer complexes. The novel synthetic strategy hybrid materials is highly efficient, avoiding waste...

We recently reported on the controlled formation of highly stable metal hydroxide nanoparticles. Growth control and stabilization particles were achieved by performing hydrolysis polycondensation reactions polymer-complexed cations, polymers being double hydrophilic block copolymers (DHBCs). The present paper focuses characterization intermediate species in process, namely mixture multivalent cations plus oppositely charged polyelectrolyte–neutral copolymers. Complexation anionic DHBCs leads...

We report experiments on aqueous foams made of solutions oligomers cationic surfactants. The degree oligomerization is varied up to 4, and two spacer lengths are used. have studied both the interfacial dilational shear rheology, single thin film properties, foamability solutions, as well aging mechanical properties 3D foams. found clear differences between oligomeric systems at all length scales. then discuss correlations different scales see how macroscopic features depend molecular...

The successive transitions of morphology in aqueous solutions interacting micelles are directly evidenced by the position q* correlation peak small angle neutron scattering profiles. As volume fraction Phi increases, successively fits to dilution laws expected for spheres and cylinders, eventually gets close one sheets when get branched. Data between swelling quantitatively analyzed terms aggregation number junction density. Varying temperature dilute regime yields end-cap energy which...

Small interfering RNAs (siRNAs) are double strand RNA fragments of short sequence (∼20 bp). interference came into focus only 13 years ago as a major biological breakthrough and, since then, many studies have described the involvement siRNA in gene silencing. Application to therapy is extremely promising, provided that appropriate vectors used. Optimising transfection efficacy strongly relies on knowledge and tuning physicochemical properties complexes, such size, surface charge internal...