Polyplexes between a double-stranded Salmon DNA and hyperbranched poly(ethyleneimine) (PEI) as well as a maltosylated PEI-Mal were incorporated into a gelatin/chitosan hydrogel scaffold. Calorimetric experiments of the polyplexes show a decrease of the melting temperature in presence of PEI and a peak splitting in presence of PEI-Mal, which can be interpreted to a partial compaction of the DNA strands in presence of PEI-Mal. When the polyplexes are incorporated into a gelatin/chitosan scaffold in the swollen state, the DNA melting peaks at 90 and 93 degrees C, respectively, indicate in both cases the release of the DNA at the surface of the hydrogel scaffold in a more compact form. Specific interactions between the PEI-Mal shell and gelatin are responsible for the tuning of the release properties in presence of the maltose units in the hyperbranched PEI.

Chemically cross-linked composite gels based on bentonite clay from Manyrak deposit (Kazakhstan Republic) and nonionic polymers, i.e., poly(hydroxyethylacrylate) and poly(acrylamide), were polymerized in situ after preliminary intercalation of monomers in an aqueous suspension of bentonite clay. By means of cryo-scanning electron microscopy, it was shown that bentonite clay is well incorporated into the gel network structure with pore sizes up to 1.5 μm. The intercalated bentonite clay can adsorb cationic surfactants as well as heavy metal ions due to electrostatic interactions. Conductometric and surface tension measurements indicate not only the adsorption of surfactants and heavy metals inside the hydrogel, but also the displacement of the critical micellization concentration (CMC) of the surfactants.

The influence of a polyampholyte, namely poly(N,N′-diallyl-N,N′-dimethyl-altmaleamic carboxylate) (PalH), on the lamellar liquid crystalline (LC) system sod ium dodecyl sulfate (SDS)/decanol/water was investigated by means of micro differential sca nning calorimetry (μ-DSC), small-angle X-ray diffraction (SAXS) and cryo scanning electron micro sc py (cryo-SEM). Aqueous solutions of PalH, in a range of 1% up to 10% and different pH values (pH 4 and pH 9), can be incorporated into the lamellar liquid crystalline system without occurrin g a macroscopic phase separation.

This paper is focused on the formation of cadmium Sulfide (CdS) nanoparticles in the poly(ethylene glycol) (PEG)-modified microemulsion consisting of sodium dodecylsulfate (SDS), xylene, pentanol, and water. Due to the presence of the polymer a bicontinuous, sponge-like microemulsion is developed, which is used as a template phase for the particle formation beside the classical w/o microemulsion. The stability and size of the particles is strongly influenced by polymer concentration and molecular weight of PEG and aggregation seems to be favoured in the sponge-like template phase. However, the process of particle aggregation in the bicontinuous phase can be hindered by increasing the concentration and molecular weight of the polymer. After solvent evaporation CdS nanoparticles with diameters of 10 nm can be redispersed, which tend to build up larger aggregate clusters.

The influence of the water soluble polymer poly(ethylene glycol) (PEG) on structure formation in the quasiternary system sodium dodecylsulfate (SDS)/pentanol-xylene/water was checked by means of conductometry, rheology, and micro differential calorimetry. The polymer induces the formation of an isotropic phase channel between the o/w and w/o microemulsion. The transition from the normal as well as from the inverse micellar to the bicontinuous phase range can be detected by conductometry, rheology as well as micro-DSC. As a result of polymer–surfactant interactions, the spontaneous curvature of the surfactant film is changed and a sponge phase is formed. The bicontinuous phase is characterized by a moderate shear viscosity, a Newtonian flow behaviour, and the disappearence of interphasal water in the heating curve of the micro-DSC. When the polymer-modified bicontinuous phase is used as a template phase for the nanoparticle formation, spherical BaSO4 nanoparticles were formed. During the following solvent evaporation process the primarily formed spherical nanoparticles aggregate to nanorods and triangular structures due to the non-restriction of the bicontinuous template phase in longitudinal direction.

In polycation-modified SDS/decanol systems, dense multilamellar structures, i.e. multilamellar vesicles are formed by self-organization, which were used as an organic template for CdS nanoparticle preparation. Specific amounts of precursors, CdCl2 and Na2S, were incorporated into the multilamellar vesicles without losing the multilamellar structure. Structural changes of the lamellar liquid crystalline template induced by the incorporation of the polycation and the inorganic precursors were investigated by differential scanning calorimetry in combination with small angle X-ray scattering. By mixing both precursors within the multilamellar vesicles CdS nanoparticles are formed. After decomposition of the vesicle template, quite different shaped and sized CdS-nanoparticles were observed by transmission electron microscopy. At lower polymer concentration spherical CdS nanoparticles of about 10 nm can be obtained. At higher polymer concentration predominantly rod-like CdS aggregates were produced with an average length of 120 nm and width of 30 nm.

This paper focuses on the characterization and use of polymer-modified phosphatidylcholine (PC)/sodium dodecyl sulfate (SDS)-based inverse microemulsions as a template phase for BaSO4 nanoparticle formation. The area of the optically clear inverse microemulsion phase in the isooctane/hexanol/water/PC/SDS system is not significantly changed by adding polyelectrolytes, i.e., poly(diallyldimethylammonium chloride) (PDADMAC), or amphoteric copolymers of diallyldimethylammonium chloride and maleamid acid to the SDS-modified inverse microemulsion. Shear experiments show non-Newtonian flow behavior and oscillation experiments show a frequency-dependent viscosity increase (dilatant behavior) of the microemulsions. Small amounts of bulk water were identified by means of differential scanning calorimetry. One can conclude that the macromolecules are incorporated into the individual droplets, and polymer-filled microemulsions are formed. The polymer-filled microemulsions were used as a template phase for the synthesis of BaSO4 nanoparticles. After solvent evaporation the nanoparticles were redispersed in water and isooctane, respectively. The polymers incorporated into the microemulsion are involved in the redispersion process and influence the size and shape of the redispersed BaSO4 particles in a specific way. The crystallization process mainly depends on the type of solvent and the polymer component added. In the presence of the cationic polyelectrolyte PDADMAC the crystallization to larger cubic crystals is inhibited, and layers consisting of polymer-stabilized spherical nanoparticles of BaSO4 (6 nm in size) will be observed.

The influence of the cationic polyelectrolyte poly(diallyldimethylammonium chloride) on structure formation in the inverse micellar region (L2 phase) of the ternary system 3 (N,N-dimethyldodecylammonio)propanesulfonate/alcohol/water has been investigated. Up to a polymer concentration in the aqueous phase of 10 wt %, an isotropic phase still exists. As the chain length of the alcohol component increases, the isotropic phase region is reduced and shifted in direction to the water corner. The isotropic polyelectrolyte-modified L2 phase of the heptanol-based microemulsion has been studied in much more detail by means of conductometric, rheological, and differential scanning calorimetry measurements. The polyelectrolyte-modified microemulsion phase shows a characteristic low shear viscosity and Newtonian flow behavior. The characteristic features of the nonpercolated microemulsion droplets are the low conductivity and the disappearance of bulk water. One can conclude from the experimental data that the individual nonpercolated polyelectrolyte-stuffed microemulsion droplets are approximately uniform in size. In addition, the area of the polyelectrolyte-modified inverse microemulsion phase with heptanol and octanol depends on the temperature. This means that the area of the L2 region can be increased by the temperature being increased from room temperature to 40degreesC. This behavior can be explained by a change in the bending elasticity of the surface film induced by Coulombic interactions between the functional groups of the polyelectrolyte and the surfactant head groups. (C) 2003 Wiley Periodicals, Inc.

The paper is focused on the formation and redispersion of monodisperse BaSO4 nanoparticles in polyelectrolyte-modified microemulsions. It is shown that a cationic polyelectrolyte of low molar mass, e.g. poly(diallyldimethylammonium chloride) (PDADMAC), can be incorporated into the individual inverse microemulsion droplets (L2 phase) consisting of heptanol, water, and an amphoteric surfactant with a sulfobetaine head group. These PDADMAC-filled microemulsion droplets can be successfully used as a template phase for the nanoparticle formation. The monodisperse BaSO4 nanoparticles are produced by a simple mixing procedure and can be redispersed after solvent evaporation without a change in particle dimensions. Dynamic and electrophoretical light scattering in combination with sedimentation experiments in the analytical ultracentrifuge of the redispersed powder show polyelectrolyte-stabilized nanoparticles with diameters of about 6nm. The polyelectrolyte shows a “size control effect”, which can be explained by the polyelectrolyte–surfactant interactions in relation to the polyelectrolyte–nanoparticle interactions during the particle growth, solvent evaporation and redispersion process. However, the approach used here opens a way to produce different types of polyelectrolyte-stabilized nanoparticles (including rare metals, semiconductors, carbonates or oxides) of very small dimensions.

The paper describes the behavior of the sulfobetaine/pentanol/toluene/water system. An isotropic inverse micellar region (L2 phase) can be observed in the oil corner. The area of the L2 phase is decreased by adding an anionic polyelectrolyte, i.e. sodium polyacrylate. The incorporation of the cationic polyelectrolyte poly(diallyl-dimethylammonium chloride) (PDADMAC) induces the extension of the isotropic phase in the direction of the water corner under the formation of an isotropic phase channel. The aim of the work presented here was to study this phase channel at constant surfactant concentration (i.e. 20%) by means of electrical conductivity, 1H NMR self-diffusion experiments, rheology, polarizing microscopy, small-angle X-ray spectroscopy, and micro-differential scanning calorimetry (DSC). Macroscopically, no indication of a phase transition is observed when going from the oil-rich side to the water-rich side. However, above a critical content of the aqueous PDADMAC solution, the diffusion coefficients are changed significantly, freezable water becomes detectable in DSC measurements, and lamellar liquid-crystalline textures become visible after shearing. This behavior can be explained by a shear-induced transition from an L2 phase to a lamellar liquid-crystalline phase, and is combined by only small viscometric and conductometric effects. The transition from the L2 to the Lα phase can be explained by a significant change of the curvature of the surfactant film due to Coulombic interactions with the polycation.

Self-assembly of matter is of fundamental importance in different fields of science, including life sciences. It is a widely used term that describes the phenomena of self-organization. From the viewpoint of a colloid scientist it is limited, according to Shinoda's concept, to the requirements of amphiphilicity in solute-solvent interactions.Starting from this concept different types of self-assembled polyelectrolyte systems have to be addressed. In the first part of this review, lyotropic liquid crystalline and hydrophobic polyelectrolytes, i.e. block polyelectrolytes, associating polyelectrolytes and polysoaps are discussed. In these cases the amphiphily is introduced into the hydrophilic polyelectrolyte chain by a partial rigidity (partial chain stiffness) or partial hydrophobicity (hydrophobic blocks or side chains).Secondly, polyelectrolyte-surfactant systems are described. Here, self-assembly is created by interactions between the polyelectrolyte and the surfactant molecules. Polyelectrolyte-surfactant interactions in dilute or semi-dilute solutions, as well as in gels or the solid state are reviewed.Lastly, self-assembly that is largely controlled by the surfactant component is discussed. In this case, polyelectrolytes can be considered as modifiers of surfactant based microemulsions, liquid crystals or foam films.The aim of this review is to provide an overview of these different fields of self-assembled polyelectrolyte systems, illustrated by some selected examples. (C) 2001 Elsevier Science Ltd. Ali rights reserved.

Polymers can be incorporated into lamellar liquid crystalline systems without the phenomena of macroscopic phase separation occurring. By playing with the inter-membrane interactions and the polymer–bilayer interactions the properties of the lamellar system can be modified significantly. This is not only of interest as a fundamental prerequisite to life, but it also opens new fields of application.

The influence of the charge density of anionic copolymers and different primary polyectrolyte complexes with a negative surface char ge on the process of binding to dodecyl-pyridinium chloride (DoPyCl) was investigated at 25 degrees C by using an electrode selective to the surfactant cation. The binding isotherms thus obtained are indicative of a cooperative binding process, which depends mainly on the charge density of the polyanion used On the other hand cooperativity is hardly evident at all in the case of primary polyanion-polycation complexes. Static light-scattering measurements support the theory that the charge density of the polyelectrolytes used influences the structural parameters of the primary complex aggregates.

The binding of the cationic surfactant dodecylpyridinum chloride (DoPyCl) to different preformed anionic charged polyelectrolyte complexes consisting of cationic copolymers with varying charge density and poly(acrylic acid, sodium salt) (PAA) has been investigated by using a potentiometric technique based on a surfactant ion solid-state electrode. The solid membrane used in the electrode consists of poly(vinyl chloride) plasticized by bis(2-ethylhexyl) phthalate. Binding isotherms are analyzed in terms of the nearest neighbor interaction model by Zimm and Bragg and for systems of reduced polyanion availability of the Scatchard plot, which indicates cooperative interactions at very low surfactant concentrations (similar to 0.01 mM). The binding constants decrease by decreasing the charge density of the cationic copolymer used. For selected systems the titration data have been complemented with static light scattering measurements.

The influence of oppositely charged polyelectrolytes and copolymers of different charge density and polyanion-polycation mixtures on the preordered lamellar liquid crystalline system sodium dodecylsulfate-decanol-water due to Coulombic interactions with special accentuation of aggregation and adsorption phenomena was examined. Small-angle X-ray results and rheological investigations are discussed with regard to changes in the interlayer spacing after introducing the polymers at various concentrations. The liquid crystalline phase was maintained, but the preformed lamellar structure was modified via penetration of the macromolecules between the hydrocarbon chains of the surfactant molecules. In the case of the polycation, strong Coulombic interactions cause a so-called ''frozen'' structure, whereas for the copolymers with decreasing charge density a ''loop'' conformation becomes possible, resulting in significantly increased interlayer spacings. Polyanions and polyanion-polycation mixtures showed phenomena of phase separation.

The influence of a cationic charged polyelectrolyte, poly(diallyldimethylammonium chloride) on the interlayer spacing of the lamellar liquid crystalline system Na-dodecylsulfate (SDS)/decanol/water was investigated by means of low-angle X-ray diffraction, polarized microscopy and rheology. It could be demonstrated that a lamellar liquid crystalline phase was still formed by introducing a cationic polymer of 5000 g/mol into the mesophase, whereas different phenomena are observed in dependence on the polymer concentration. The average thickness of the layer, that means the layer repeat unit, is not influenced in the range of lower polymer concentration (up to 1%). At 2% polymer a lamellar liquid crystalline phase formed by SDS and decanol molecules and a frozen structure including polymer chains existing side by side. In a range of 5% and 10% polymer the frozen structure is the dominant one. It is assumed that electrostatic interactions determine the location of the polymer in the water layer between the surfactant head groups. Rheological investigations support the proposed model.

The influence of oppositely charged polyelectrolytes on the interlayer spacing of the lamellar liquid crystalline system hexadecyltrimethylammonium bromide/decanol/water was investigated by means of small angle X-ray diffraction and polarized microscopy. It could be demonstrated that a liquid crystalline phase was still formed by introducing a cationic polymer of low molecular weight into the lamellar structure. A disordering of the preformed structure and a decrease of the interlayer spacing occurred via penetration of the macromolecule between the hydrocarbon chains of the surfactant molecules. By using a ''penetration'' model for the disordering phenomena, ''folded'' and ''telescoped'' structures are discussed. The polyanion in a polyanion/polycation mixture gave the same structural change as when added alone.