Polyelectrolyte complexes. VI. Polycation structure,polyanion molar mass,and polyion concentration effects on complex nanoparticles based on poly(sodium 2‐acrylamido‐2‐methylpropanesulfonate)

The formation and characterization of some interpolyelectrolyte complex (IPEC) nanoparticles based on poly(sodium 2‐acrylamido‐2‐methylpropanesulfonate) (NaPAMPS), as a function of the polycation structure, polyanion molar mass, and polyion concentration, were followed in this work. Poly(diallyldimethylammonium chloride) and two polycations (PCs) containing (N,N‐dimethyl‐2‐hydroxypropyleneammonium chloride) units in the backbone (PCA₅ and PCA₅D₁) were used as starting polyions. The complex stoichiometry, (n^?/n⁺)_iso, was pointed out by optical density at 500 nm (OD₅₀₀), polyelectrolyte titration, and dynamic light scattering. IPEC nanoparticle sizes were influenced by the polycation structure and polyanion molar mass only before the complex stoichiometry, which was higher for the more hydrophilic polycations (PCA₅ and PCA₅D₁) and for a higher NaPAMPS molar mass, and were almost independent of these factors after that, at a flow rate of the added polyion of about 0.28 mL × (mL PC)^?1 × h^?1. The IPEC nanoparticle sizes remained almost constant for more than 2 weeks, both before and after the complex stoichiometry, at low concentrations of polyions. NIPECs as stable colloidal dispersions with positive charges in excess were prepared at a ratio between charges (n^?/n⁺) of 0.7, and their storage colloidal stability, as a function of the polycation structure and polyion concentration (from 0.8 to ca. 7.8 mmol/L), was demonstrated. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 2495–2505, 2004     

Thermochemically induced binding of methyl orange to polycations containing primary amine groups

The thermochemical transformation of electrostatically formed complexes of methyl orange (MO) with polycations containing primary amine groups such as ammonium salts afforded new polymers with a high concentration of covalently bound 4‐N,N‐dimethylaminoazobenzene groups in the side chain. Poly(allylamine hydrochloride) and poly(β‐aminoethylene acrylamide hydrochloride) were employed as support polycations for MO. The transformation of sulfonate–ammonium ion pairs into sulfonamide bonds, via heating at an elevated temperature, was supported by the polymer properties before and after the thermal treatment. The polymer structure changes were monitored with elemental analysis, Fourier transform infrared, ¹H NMR, and ultraviolet–visible absorption spectroscopy, and thermogravimetric analysis. The spacer length between the backbone and azobenzene structures used as side chains strongly influenced the polymer properties before and after the heat‐induced reaction. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5898–5908, 2006     

Cationic polyelectrolytes. III. Nitrile-group reaction of macromolecular compounds with N,N-dialkylaminoalkylamines

The chemical reaction in aqueous medium of polyacrylonitrile and acrylonitrile–vinyl acetate co-polymer using asymmetrical diamines of H₂N? (CH₂)_m? NR₂ (m = 2,3) structure was studied. It was found that the nitrile group is modified to an dialkylaminoalkylacrylamide group; also determined were the reaction conditions required to obtain the highest degree of chemical transformation of the nitrile groups. All modified compounds were characterized by analytical spectroscopy (IR and ¹H NMR) and by rheological methods. It was also established that glutaronitrile can be used as a low-molecular-weight model to study the chemical transformation of nitrile groups in polyacrylonitrile and related polymers.     

Cationic polyelectrolytes. II. Amination of chloromethylated polystyrene with hydroxyalkylic secondary amines

The reaction of chloromethylated polystyrene with methyl(2- hydroxyethyl)amine and butyle (2-hydroxyethyl)amine was studied kinetically. The reaction of benzyl chloride with these amines was also investigated for comparison. N,N-dimethylformamide and dioxane were used as solvents. The reactions of benzyl chloride with the two amines in these solvents took place according to normal kinetics of the second order. Reaction kinetics depend on the nature of the amine and solvent in Chloromethylated polystyrene reactions. In dioxane the self-accelerating effect of the reaction for β ? 0.5 is apparent. Steric hindrance of the reaction, beginning with a conversion degree of about 75%, wss observed for butyl(2-hydroxyethyl)amine in N,N-dimethylformamide. This self-accelerating effect is observed in dioxane at the same reaction degree. The activation energies and frequency factors were calculated for the amination of benzyl chloride and chloromethylated polystyrene with the two amines in N,N-dimethylformamide and dioxane.     

Two-stage latexes of polystyrene acrylates

ABSTRACT

The modification of decomposition rate of the potassium persulfate initiator during the synthesis of “two-stage latexes” polystyrene-ethyl acrylate (EtA) of butyl acrylale (BuA) and of 2-ethylhexyl acrylate (EHA) is studied. This rate is minimum for BuA and maximum for EHA, in good agreement with the value of solubility parameters. The appearance of poryacrvlaf.es determines the existence of water bonded to the polar polymer. The amount of water bonded increases in the sequence PEtA?PBuA?PEHA, function of the modification of the diameters of the particles resulted from the latexes obtained.     

Study on metal complexes of chelating resins bearing iminodiacetate groups

Cu(II), Co(II) and Ni(II) complexes of chelating resins (CR) bearing iminodiacetate (IDA) ligands were prepared. The CR-metal complexes were characterized by FT-IR spectroscopy, X-ray diffraction (XRD), thermal behavior (TG and DTG) under nitrogen atmosphere, and electron paramagnetic resonance (EPR). FT-IR spectra of the CR-metal complexes showed the characteristic bands of CR were still present but red-shifted after the metal complexation, and new bands assigned to Me-N bonds were observed. Thermal behavior of the metal-CR complexes supported the metal complexation, metal complexation leading to the decrease of the thermal stability of the CR, the lowest thermal stability being found when the highest amount of Cu(II) was loaded. Based on the EPR results and the thermal behavior of Cu(II)-CR complexes, the scheme for the complexation of Cu(II) on the CR was suggested.     

Growth and thermoelectric properties of FeSb<Subscript>2</Subscript> films produced by pulsed laser deposition

Thermoelectric FeSb₂ films were produced by pulsed laser deposition on silica substrates in a low-pressure Ar environment. The growth conditions for near phase-pure FeSb₂ films were confirmed to be optimized at a substrate temperature of 425°C, an Ar pressure of 2 Pa, and deposition time of 3 h by ablating specifically prepared compound targets made of Fe and Sb powders in atomic ratio of 1:4. The thermoelectric transport properties of FeSb₂ films were investigated. Pulsed laser deposition was demonstrated as a method for production of good-quality FeSb₂ films.     

Amidoalkylation of heteroaromatic compounds with adducts of acyl chlorides and 3,4-dihydroisoquinoline and isoquinoline

The N-acyliminium intermediates of 3,4-dihydroisoquinoline and salts of isoquinoline with acyl chlorides were successfully used as amidoalkylating reagents toward synthesis of heterocyclic aromatics as indole, pyrrole, thiophene and pyrazine.     

PAN composite membrane with different solvent affinities controlled by surface modification methods

Polyacrylonitrile (PAN) composite membranes with surface properties designed by either a chemical modification with ethylenediamine (EDA), or layer‐by‐layer (LbL) polyelectrolyte adsorption were investigated in this paper. Fourier‐transformed infrared (FTIR) spectroscopy and streaming potential measurements showed that the first step of the reaction with EDA in gas phase was the formation of ammonium salts with the reactive carboxylic groups present on the surface of the starting membrane. Part of the ammonium carboxylate groups was transformed in secondary amide linkages by a heat‐induced reaction. Poly(sodium styrenesulfonate) (NaPSS) and a polycation containing about 95 mol % of N,N‐dimethyl‐2‐hydroxypropyleneammonium chloride units in the backbone (PCA₅) were used as opposite polyions in the LbL film construction. The adsorbed polyion amount per every layer was controlled by the nature and concentration of the supporting electrolyte in polyelectrolyte deposition solution (NaBr and KBr). An almost linear increase of the adsorbed polyion amount versus the layer pair number was observed. The swelling degree (SD) in pure alcohols of the LbL‐modified PAN composite membrane decreased with the increase of the solvent polarity and with the decrease of the pore volume by pore filling with polyelectrolyte complex multilayer. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4161–4171, 2005