Biodegradable Interpolycomplexes for Anti-Erosion Stabilization of Soil and Sand.

A linear anionic polysaccharide, sodium alginate, electrostatically interacts with a cationic polysaccharide, quaternized hydroxyethyl cellulose ethoxylate, in aqueous solution, thus giving an interpolyelectrolyte complex. Aqueous solutions of the initial polysaccharides and polycomplexes with an excess of the cationic or anionic polymers were used for the stabilization of soil and sand against water erosion. Physicochemical, mechanical and biological properties of the polymers and coatings were characterized by gravimetric analysis, viscosimetry, mechanical strength assessment, cell viability, and cell-mediated degradation with the following main conclusions.

Biocidal Coatings from Complexes of Carboxylated Latex Particles and a Linear Cationic Polymer.

A linear polycation, poly(diallyldimethylammonium chloride), electrostatically interacts with anionic latex particles from a carboxylated butadiene-styrene copolymer in aqueous solution thus forming an interpolyelectrolyte complex. A mutual neutralization of oppositely charged latex and polycation groups occurs at = latex/polycation = 50 ratio. At = 27, an ultimate polycation adsorption is reached, resulting in the formation of positive polycomplex particles, while at ˂ 27, two-component systems are formed composed of positive polycomplex particles and free polycation.

A Dramatic Change in Rheological Behavior of a Clay Material Caused by a Minor Addition of Hydrophilic and Amphiphilic Polyelectrolytes.

Wide usage of clay-based materials in industry requires investigations concerning efficient modification techniques to control their mechanical behavior in aqueous media. The challenging problem in this field involves minimization of the modifying agent content to provide marked changes in the operating characteristics of the material. In this work, the physicochemical, mechanical and structural aspects of the interaction of capillary water-saturated kaolinite with polyelectrolytes were studied.

Initial-Stage Dynamics of Flocculation of Cationic Colloidal Particles Induced by Negatively Charged Polyelectrolytes, Polyelectrolyte Complexes, and Microgels Studied Using Standardized Colloid Mixing.

The initial-stage dynamics of flocculation of positively charged latex particles induced by polyelectrolytes (PEs) and polyelectrolyte complexes (PECs), composed of linear polyacrylic acid (PAA) and a PAA-based hydrophilic microgel (PAA#) with a small amount of a linear polycation, was comparatively analyzed by applying the standardized colloidal mixing procedure. Based on the rate of flocculation, this method allows us to investigate the dynamics of flocculation immediately after the onset. In addition to confirming the prediction made regarding the initial rate of flocculation with linear polyanions-which was mostly similar to that observed in negatively charged colloids with positively charged PEs-we have confirmed two important new results regarding the microgel: (1) the increase of the initial rate is less markedly affected by the microgel concentration than by the linear polymer concentration, which can be explained by the fact that the three-dimensional (3D) cross-linked structure of the microgel that does not deform as easily as the linear structure upon touching the colloidal surface; and (2) there is a remarkable increase of the initial rate due to the contribution of instant aggregation of the negatively charged microgel induced by the polycation adsorption.

Two-phase channel structures based on alpha-cyclodextrin-polyethylene glycol inclusion complexes.

Wide-angle X-ray scattering observations of alpha-cyclodextrin (CD)-poly(ethylene glycol) (PEG) inclusion complexes (ICs) have shown for the first time that two crystalline columnar modifications (forms I and II) are produced in the process of their formation. This was made possible by precise azimuthal X-ray diffraction scanning of oriented IC samples. Form I is characterized by CDs threaded onto PEG chains and arranged along channels in the order head-to-head/tail-to-tail, while form II is formed by unbound CDs also arranged into columns in a head-to-tail and also possibly a head-to-head/tail-to-tail manner, probably as a result of template crystallization on the form I IC crystals.