No abstract

Composite solid surfaces with high content of functional groups (FGs) are useful materials in different types of applications requiring stimuli-responsive “hard/soft” architectures, their improved properties rising from the combination of organic–inorganic parts. Among different types of weak polyelectrolytes, poly­(ethyleneimine) (PEI) is of great interest in the construction of composite systems with thin layer-by-layer (LbL) organic films due to the large number of amino groups per unit mass of polymer. Herein, the spherical silica microparticles were modified with linear (L) or branched (B) PEI chains using LbL deposition of a copper complex (PEIL–Cu2+ or PEIB–Cu2+) and poly­(acrylic acid) (PAA), glutaraldehyde selective cross-linking, followed by copper and PAA extraction from the multilayer. The newly formed silica/(PEIL)10 and silica/(PEIB)10 composites were used in batch and column sorption/desorption experiments of four heavy metal ions (Cu2+, Ni2+, Co2+, and Cd2+). In noncompetitive conditions ([FG]/Σ­[M2+] > 9), all heavy metal ions were retained on composites, demonstrating the potential application of the prepared functional microparticles in surface water treatment. However, in competitive conditions ([FG]/Σ­[M2+] < 9), only Cu2+ is sorbed in high amount (∼2.5 mmol·g–1 PEI) on composites, with simultaneous displacement of already sorbed ions, demonstrating the solid-phase extraction and chromatographic properties of the synthesized silica/(PEIL) n and silica/(PEIB) n composites.

No abstract

No abstract

No abstract

No abstract

Abstract. This study aims to evidence the formation of stable polyelectrolyte complex particles as colloidal dispersions using some weak polyelectrolytes: chitosan and poly(allylamine hydrochloride) as polycations and poly(acrylic acid) (PAA) and poly(2-acrylamido-2-methylpropanesulfonic acid -co -acrylic acid) (PAMPSAA) as polyanions. Polyelectrolyte complex particles as colloidal dispersion were prepared by controlled mixing of the oppositely charged polymers, with a constant addition rate. The influences of the polyelectrolytes structure and the molar ratio between ionic charges on the morphology, size, and colloidal stability of the complex particles have been deeply investigated by turbidimetry, dynamic light scattering and atomic force microscopy. A strong influence of polyanion structure on the values of molar ratio n -/n + when neutral complex particles were obtained has been noticed, which shifts from the theoretical value of 1.0, observed when PAA was used, to 0.7 for PAMPSAA based complexes. The polyions chain characteristics influenced the size and shape of the complexes, larger particles being obtained when chitosan was used, for the same polyanion, and when PAMPSAA was used, for the same polycation.

No abstract