One Pot Synthesis of Amphiphilic Hyperbranched Poly-(amino ester)and Its Dynamic Surface Activity

Amphiphilic hyperbranched poly(amino ester)s with hydrophilic multi‐ethoxylated triacrylate backbone and hydrophobic long alkyl side chain were firstly synthesized via one pot Michael addition polymerization. The poly‐(amino ester) could dissolve in cold water and self‐assemble into loose micelle. Under 50–1000 ms bubble, the dynamic surface tension (DST) of the poly(amino ester) aqueous solution (0.5 wt%) still maintained in the range of 32–28 mN/m. The aqueous solutions of poly(amino ester)s with different molecular weights showed the lower critical solution temperature (LCST) in the range of 8–50°C, which could also be tuned by its pH. Capped with hydrophobic groups on the terminal units and partially neutralized with acid, the poly(amino ester)s still kept their stable dynamic surfactant behaviors, indicating promising application.     

Properties of mixed protein/surfactant adsorption layers

The adsorption isotherms, adsorption kinetics and surface rheological properties of β-lactoglobulin, β-casein, in the absence and presence of Tween 20 were measured. To study the adsorption process (isotherms and kinetics) at the water–air interface the pendant drop technique (axial drop shape analysis, ADSA), and ring tensiometry were used. The surface shear rheological parameters were measured with a torsion pendulum set-up. Also, data of the equilibrium film thickness and surface diffusion coefficients obtained from fluorescence recovery after photobleaching (FRAP) measurements are used to understand the competitive adsorption mechanism. The adsorption process and shear rheological behaviour of the studied systems show a rather complex behaviour which depends most of all on the system's composition. At high protein or surfactant content the behaviour is controlled by the main component while for the more mixed systems the adsorption process is complex and consists of partial adsorption, surfactant–protein interaction and protein rearrangement as a function of surface coverage. The results obtained illustrate that all these processes must be taken into account in future new theoretical models to be derived for such systems.     

Highly conductive soluble terpolymers of aniline,toluidine, and o‐aminobenzoic acid/m‐aminobenzenesulfonic acid

Two series of terpolymers, one of o‐/m‐toluidine and aniline with o‐aminobenzoic acid and the other of o‐/m‐toluidine and aniline with m‐aminobenzenesulfonic acid, have been synthesized by oxidative polymerization via an emulsion method with ammonium persulfate as the oxidant and HCl as the external dopant. The terpolymers exhibit excellent solubility and retain the high conductivity (∼1 S cm⁻¹) characteristic of the unsubstituted homopolymer, polyaniline. The terpolymers also possess higher thermal stability than polyaniline. This can be attributed to the presence of internal doping groups and substituents, which introduce flexibility to the otherwise rigid polyaniline backbone. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3040–3048, 2005     

Application of the extended DLVO theory—the stability of alatrofloxacin mesylate solutions

Electrophoretic mobility and contact angle measurements have been made on alatrofloxacin mesylate and its formulations which were protected from or exposed to light, and its degradation product compound (F). In aqueous solution, the light-protected alatrofloxacin mesylate had a zeta-potential of +19 mV, a negligible electron-acceptor (γ_i⁺) surface tension parameter and an electron-donor surface tension parameter γ_i⁻=32.5 mJ m⁻², which was higher than that of water. This caused the particles to be very hydrophilic and to form very stable suspensions in aqueous solution due, mainly, to a net Lewis acid–base (polar) repulsion. After the suspensions were exposed to light, the zeta-potential of the degradation product increassed to +37.8 mV, but the electron-donor surface tension parameter decreased to γ_i⁻=8 mJ m⁻², making the molecules or particles very hydrophobic and causing them to flocculate. The energies of attraction in the latter case were mainly hydrophobic (90%) with about 10% resulting from van der Waals forces.     

Incompressible SPH simulation of water entry of a free‐falling object

In this paper an incompressible smoothed particle hydrodynamics (Incom‐SPH) model is used to simulate the interactions between the free surface flow and a moving object. Incom‐SPH method is a two‐step semi‐implicit hydrodynamic formulation of the SPH algorithm and is capable of accurately treating the free surface deformations and impact forces during the solid–fluid interactions. For a free‐falling object, its motion is tracked by an additional Lagrangian algorithm based on Newton's law to couple with the Incom‐SPH program. The developed model is employed to investigate the water entry of a free‐falling wedge. The accuracy of the computations is validated by the good agreement in predicting the relevant hydrokinematic and hydrodynamic parameters. Finally, a numerical test is performed to study the influence of spatial resolution on the water entry features. The Incom‐SPH modeling coupled with the solid–fluid interaction algorithm could provide a promising computational tool to predict the slamming problems in coastal and offshore engineering. Copyright © 2008 John Wiley & Sons, Ltd.     

Evidence for a new metastable crystalline phase of strontium nitrate

The undercooling of aqueous solutions of strontium nitrate a few mm³ in volume or microsized by dispersion within an emulsion is investigated. The experimental results are consistent with a succession of transformations in undercooled solutions of binaries. Following concentration, the undercoolings are from 14°C to 20°C for macrosamples or from 39°C to 60°C with emulsions. However it is observed that Sr(NO₃)₂ crystallizes into a metastable phase which can be preserved for a long time. The existence of this metastable crystalline phase has been evidenced by Differential Scanning Calorimetry and by an original evaporation method. The phase diagram, including the metastable phase, is presented.     

Reactivity studies of carbon,phosphorus and sulfur‐based acyl sites with tertiary oximes in gemini surfactants

Kinetic studies of the reactions of tertiary oximes (monoisonitroso acetone; MINA and butane 2,3 dione monooxime; BDMO) with some carboxylate (p‐nitrophenyl acetate and p‐nitrophenyl benzoate), phosphate (p‐nitrophenyl diphenyl phosphate and bis (2,4‐dinitrophenyl) phosphate) and sulfonate (p‐nitrophenyl p‐toluene sulphonate) esters in gemini surfactants have been conducted. The observed first‐order rate constant versus surfactant profiles show micelle‐assisted bimolecular reactions involving interfacial ion exchange between bulk aqueous media and micellar pseudophase. Experimental results showed that MINA exhibited better nucleophilic activity towards ester cleavage than BDMO. Pseudophase model has been applied in order to determine micellar second‐order rate constants and binding constants. Copyright © 2013 John Wiley & Sons, Ltd.