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Minerals with different particle size and morphology were prepared, and the effects of different preparation methods were analyzed. The minerals, fluoroapatites, were synthesized from CaCl2, Na2HPO4 and KF by precipitation in aqueous solution, precipitation in microemulsions and by a biomimetic synthesis in a gelatine matrix. Several characterization methods were used. The effects of varying the synthesis...
Colloidal dispersions of solid triglycerides as potential drug carriers are preferably prepared by high-pressure homogenization of molten triglycerides in an aqueous phase with adequate stabilizers and subsequent crystallization of the emulsified lipid particles. The influence of several commercial ionic and nonionic stabilizers and their blends with phosholipid on the crystallization and subsequent...
It has long been known that solid particles can act as very effective stabilisers of emulsions in the absence of surfactant. The particles are usually small in relation to the emulsion drop size (say, particle radius 0.1 times the drop radius or less). There are apparent similarities in the ways in which particles and low-molar-mass surfactants act as emulsion stabilisers. For systems with roughly...
Zirconia micro parts were fabricated by a sequence of process steps. A master model (a positive to the final ceramic part) was copied into a silicone rubber mould insert and the rubber mould insert was used for producing ZrO2 prototypes by hot moulding. Hot moulding was carried out with suspensions of ZrO2 in a mixture of paraffin and a dispersant. The rheological properties of different commercial...
The application of adsorbents in odour control can be traced back for centuries, but with low efficiency. Owing to the variety of odours and the sensitivity of the population, powerful techniques for odour control have to be developed. Specific sorption processes are promising. Surface modification of silica gel is a possible way to increase the specificity of the adsorbents. A simple method is introduced...
This article discusses the dynamical properties of homogeneous colloid—polymer blends consisting of hairy nanospheres and linear polymer chains, respectively. Two different model systems of hairy particles have been prepared: a system with comparatively short hairs off molecular weight below the entanglement regime, polyorganosiloxane microgels grafted with polystyrene hairs of molecular weight 13,000...
A study on the osmotic coefficient of polyelectrolyte brushes in aqueous solution is reported. The systems studied here consist of a solid polystyrene core with chemically grafted linear poly(sodium styrenesulfonate) chains. The osmotic pressure of the counterions of these spherical polyelectrolyte brushes in aqueous solution without added salt has been investigated in the dilute regime (0.05-0.50...
Cyclodextrins and cucurbit[6]uril are macrocyclic host molecules with rigid cavities. They are able to form complexes with a large number of organic molecules in solution. The fixation of cyclodextrins on polymer surfaces offers new applications for the use of textiles if the ability to form complexes is maintained. The cyclodextrins can act as depots for cosmetics, pharmaceutics, fragrances and perfumes...
(Flow-)field-flow fractionation was used for the characterization of colloidal particles. The separation according to the hydrodynamic diameter is used in the range 20–400 nm, and differences in diameter exceeding 20–30% are well recognized. The method is rather tolerant of the type and the architecture of the sample. Coupling with a light scattering and a refractive index detector gives the molar-mass...
The behavior of liquid molecules, confined in nanometerscale spaces or at solid—liquid interfaces, is quite different from that in the bulk, which is attributed to the surface-induced structuring of liquids. The structuring of liquids at solid—liquid interfaces was investigated by employing new approaches based on surface force measurement. The combination of surface force measurement and Fourier...
Crystalline monomolecular cell surface layers (S layers) represent one of the most commonly observed cell envelope components of prokaryotic organisms (bacteria and archaea). Owing to their high degree of structural regularity, S layers represent interesting model systems for studies on structure, genetics, functions and dynamic aspects of assembly of supramolecular structures. One of the key features...
The novel amphiphile 9-octadecyladenine (AdC18), which has an adenine headgroup and a long hydrocarbon chain, was synthesized. Its monolayer behavior and its interactions with three guest molecules were investigated at the air—water interface by means of surface pressure—area isotherms. The structures of multilayer Langmuir—Blodgett (LB) films of AdC18 were characterized by Fourier transform IR spectroscopy...
The surface pressure—molecular area isotherms and the texture features of 9-hydroxyhexa-decanoic acid monolayers are studied using the film-balance technique and Brewster-angle microscopy. In the two-phase coexistence region, homogeneously reflecting condensed-phase domains of a regular shape are formed. The 9-hydroxy-hexadecanoic acid monolayers show an unusual low, but linear, increase in the transition...
In the framework of the parametric method 3 quantum chemical approximation reasonable values are obtained for the thermo-dynamic characteristics of the cluster formation for the fatty alcohol series CnH2n+1OH (n = 8–16) with various structures at the air/water interface. The calculated values of the enthalpy, the entropy and the Gibbs energy for the formation of a definite cluster structure can be...
The role of the buoyancy force for the development of the auto-oscillations of the surface tension is considered by comparison of the oscillation characteristics for the corresponding pairs of fatty acids and aliphatic alcohols. The effect of buoyancy on the oscillation characteristics is negligibly small for systems with low solubility surfactants, such as octanol, octanoic acid or diethyl phthalate;...
A large number of different NMR methods are of great usefulness in the investigation of molecular mobility in organic bulk systems, while studies at interfaces are rare owing to the low intrinsic sensitivity of NMR methods. This article presents two examples of the application of spin resonance in investigations of polymers at interfaces, employing polymer-coated colloids: Applying 1H liquid-state...
An ionically charged Lα phase can be prepared without shear by mixing a small amount of meth-ylformiate to an L3 phase from alkyldimethylaminoxide, hexanol and water. If the structural transformation induced by the hydrolysis reaction of the ester is carried out in the presence of a high magnetic field, a macroscopically aligned lamellar phase is obtained. The alignment process was studied by 2H NMR...
Two new polymer surfactants consisting of a polysiloxane backbone with amphiphilic side chains of the nonionic oligo (ethylene oxide) type have been synthesized. The phase behavior of aqueous solutions of the low-molecular-weight surfactants, from which the side chains are formed, and of the polymer surfactants was characterized by polarizing microscopy and 2H NMR spectroscopy. Both polymers form...
The solvatochromic behavior of 2,6-dichloro-4-(2,4,6-tri-phenyl-1-pyridinium-1-yl) phenolate (WB), 1-methyl-8-oxyquinolinium betaine (QB), and sodium 1-methyl-8-oxyquinolinium betaine-5-sulfo-nate (QBS) has been studied in the presence of spherical, and rod-shaped micelles of 1-hexadecyltrim-ethylammonium bromide (CTABr) and 1-hexadecylpyridinium bromide. Rod-shaped aggregates were obtained either...
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