Lako Lakov

Amphiphilic polyelectrolyte networks derived from 2-oxazolines

Abstract Ionene graft copolymers and networks containing quaternary ammonium groups as linkages have been prepared by termination of living mono- and bifunctional poly(2-methyl-2-oxazoline) and poly(2-phenyl-2-oxazoline) with poly(dimethylaminoethyl methacrylate). Ionene networks of different density with p , p ′-dichloroxylene and poly(2-alkyloxazoline)s as cross-linkers have been synthesized. The obtained graft and crosslinked copolymers are well defined and with controlled hydrophilic–hydrophobic balance. Viscosity examination and potentiometric titration of some of the products were carried out. Sorption ability towards Cu 2+ , Ni 2+ , Mn 2+ , Fe 3+ and anion-exchange capacity were investigated as well. The pH dependence of the sorption of metal ions was evaluated.

Sorption of Co(II), Ni(II), Ag(I) and Au(III) on pyrazolone-containing inorganic sorbents

The sorption capacity of 3-methyl-1-phenyl-pyrazolone-5 (HMPP)- modified inorganic sorbents has been investigated. The new sorbents are suitable for simultaneous concentration of the 3d elements being investigated over a wide pH range. Choosing appropriate pH values for the corresponding elements, it is possible to achieve their separate extraction.

Characterization of hybrid fillers based on carbon black of different types obtained by impregnation

The paper presents the investigations on obtaining dual phase fillers with preset silica content running a successful impregnation of two completely different types of conventional carbon black with silicasol. The hybrid fillers studied were characterized by atomic absorption spectroscopy and inductively coupled plasma–optical emission spectroscopy. The total pore volume, the average pore diameter, the specific surface area, the oil absorption number, and iodine adsorption of the fillers were also investigated. The distribution of both phases within the hybrid filler obtained and their interpenetration were investigated with scanning transmission electron microscopy-energy dispersive X-ray spectroscopy. The hybrid products obtained were investigated as reinforcing fillers of natural rubber-based composites. The results obtained show that the suggested impregnation with silicasol of conventional carbon black is a perspective method for preparation of carbon-silica dual phase fillers. The method provides an easy control over the quantitative ratio between the two phases. The fillers thus prepared do not change significantly the curing and mechanical characteristics of the vulcanizates, but improve their thermal aging resistance. The isolation of the carbon black aggregates by the silica phase, and the interpenetration of the two phases is a prerequisite to obtain elastomer composites of good mechanical and microwave properties suitable for producing of microwave shielding devices.

Phosphazenes on diatomaceous earths in water adsorption

Hexachlorocyclotriphosphazene (T) and poly-bis-(trifluoroethoxy)phosphazene (A) deposited separately on wide-pore kieselguhr supports result in composite adsorbents of an increased adsorption capacity for water vapour per unit surface area. Deposition alters the adsorption behaviour of T and A themselves due to high dispersion and conformation changes of polymer chains within the pores in comparison with the initial solid state.

Water vapour adsorption on phosphazenes

We report the adsorption isotherms of water vapour at 22°C on six representatives of the phosphazene family: hexachlorocyclotriphosphazene (I), bis-(dimethylamino)-tetrachlorocyclotriphosphazene (II), bis-(dimethylamino)-bis-(trifluoroethoxy)-dichlorocyclotriphosphazene (III), octabutylaminocyclotetraphosphazene (IV), phospham (V) and poly-bis-(trifluoroethoxy)phosphazene (VI). The phosphazenes chosen differ in how their N-P backbone is built up (cyclic I-IV, cyclomatrix V and linear VI), in their degree of polymerization (trimers I-III, tetramer IV and polymers V and VI) as well as in the type of substituents at the phosphorous atoms