Search results for "Polyelectrolyte"
showing 10 items of 214 documents
Polyacrylate Protonation in Various Aqueous Ionic Media at Different Temperatures and Ionic Strengths
2000
The protonation constants of the polyacrylate anion (molecular mass 2000 Da) in Et4NI, Me4NCl, LiCl, LiNO3, NaCl, NaNO3, and KCl aqueous solution, were determined in a wide range of ionic strengths. A three-parameter approximation was used to express protonation constants as a function of the dissociation degree α, and their dependence on ionic strength was considered using a simple polynomial expansion. Differences in log KH between different data in different media were interpreted in terms of weak complex formation between polyacrylate and alkali metal cations. Measurements were also performed at different temperatures (15 ≤ T/°C ≤ 55) in order to calculate enthalpy and entropy changes f…
Sequestration of organometallic compounds by natural organic matter. binding of trimethyltin(IV) by fulvic and alginic acids
2006
The binding capacity of fulvic and alginic acids towards trimethyl tin(IV) cation was quantitatively determined in order to evaluate the sequestering ability of toxic organometallic compounds by natural organic matter. Investigations were performed in the pH range of natural waters (5–8.5) where the carboxylate groups, largely present in both sequestering agents, are the main binding sites. A chemical interaction model, according to which both the protonation of polyelectrolyte ligands and the hydrolysis of the organotin cation in NaCl aqueous solution were considered, was used to define the speciation of the systems under investigation. Measurements performed at different ionic strength va…
New Self-Assembling Polyaspartamide-Based Brush Copolymers Obtained by Atom Transfer Radical Polymerization
2009
A simple and efficient method for the synthesis of polyaspartamide-based brush copolymers using Atom Transfer Radical Polymerization (ATRP) is here presented. The syntheses were performed by using two subsequent steps. In the first step the macroinitiator was obtained by the conjugation of a proper number of 2-bromoisobutyryl bromide (BIB) residues to the R, -poly(N-2-hydroxyethyl)-D,L-aspartamide (PHEA) side chains, obtaining the PHEA-BIB copolymer. PHEA-BIB copolymer was used as “multi-functional macroinitiator” for the polymerization via ATRP of hydrophilic methacrylic monomers, such as methacrylic acid (MA), obtaining PHEA-IB-poly(MA) copolymer, sodium methacrylate (MANa+), obtaining PH…
Polyacrylates in aqueous solution. The dependence of protonation on molecular weight, ionic medium and ionic strength
2003
Abstract The protonation constants of polyacrylates with different molecular weights ( W =2000–750 000 Da) were determined in different ionic media (alkali metal chlorides and nitrates, tetraalkylammonium chlorides), at 25 °C, by potentiometric measurements (H + –glass electrode). Literature data were also considered. Different models used to analyse protonation data were compared: the first was the modified Henderson–Hasselbalch two-parameter equation, and the second was the three-parameter equation proposed by Hogfeldt. The dependence on the ionic strength of the different supporting electrolytes and all the protonation parameters involved in the two models showed the trend Et 4 N + ≫Li +…
Static and dynamic light scattering by aqueous polyelectrolyte solutions: effect of molecular weight, charge density and added salt
1990
Abstract Aqueous solutions of quaternized poly(2-vinylpyridine) were investigated by static (SLS) and dynamic (DLS) light scattering over a wide range of polyelectrolyte, c pe , and salt concentrations, c s (10 −3 ≤ c pe ≤ 10 2 gl −1 , 10 −5.5 ≤ c s ≤ 10 −1 moll −1 ). Using DLS the cooperative diffusion coefficient D was measured as a function of c pe and c s . D exhibits a characteristic behaviour in each of three different concentration regimes. In the ‘dilute lattice’ regime, where λ = c pe c s ⪡ 1 , one diffusion coefficient is observed. In the transition regime, where λ ≈ 1, D increases with increasing polyelectrolyte concentration and a slow diffusive mode gradually appears. For λ ⪢ 1…
Investigation of the Interpolymer Complex between Hydroxypropyl Cellulose and Maleic Acid-Styrene Copolymer, 1
2004
The hydrogen bonding-interpolymer association of hydroxypropyl cellulose (HPC) with maleic acid-styrene (MAc-S) copolymer has been investigated in dilute aqueous solution by viscometry, turbidimetry and potentiometry. At a mixing ration between MAc-S and HPC of 10:90, the solution exhibits a phase separation upon heating, while for other mixing ration no phase separation could be detected. The stability of the interpolymer complex (IPC) increases as the temperatures rises. The stoichiometry of the IPC, in mole units, was estimated as being MAc-S:HPC=5:2. The thermodynamic functions (enthalpy and entropy) of the complexation process have been determined.
NEW GRAFT COPOLYMERS OF HYALURONIC ACID AND POLYLACTIC ACID: SYNTHESIS AND CHARACTERIZATION
2006
Abstract New graft copolymers have been synthesized, using hyaluronic acid (HA) as a hydrophilic backbone and polylactic acid (PLA) as an aliphatic polyester in order to obtain new polymeric derivatives of HA able to hydrophobically associate in an aqueous medium. Hyaluronic acid with low molecular weight was made soluble in organic solvent by transformation to its tetrabutylammonium (TBA) salt. Using the HA–TBA derivative, the reaction was performed in dimethylsulfoxide adding as a reagent the N -hydroxysuccinimide derivative of PLA. Two HA–PLA graft copolymers have been synthesized and characterized by FT-IR, 1 H NMR spectroscopy and gel permeation chromatography. The interaction between …
The biomaterial polyphosphate blocks stoichiometric binding of the SARS-CoV-2 S-protein to the cellular ACE2 receptor
2020
The effect of the polyanionic polymer of inorganic polyphosphate (polyP) involved in innate immunity on the binding of the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein to the cellular ACE2 receptor was studied. The RBD surface comprises a basic amino acid stretch of four arginine residues which interact with the physiological polyP (polyP40) and polyP3. Subsequently, the interaction of RBD with ACE2 is sensitively inhibited. After the chemical modification of arginine, an increased inhibition by polyP, at a 1 : 1 molar ratio (polyP : RBP), is measured already at 0.1 μg mL−1. Heparin was ineffective. The results suggest a potential therapeutic benefit of polyP against SARS-C…
Polyelectrolyte properties of filamentous biopolymers and their consequences in biological fluids.
2014
Anionic polyelectrolyte filaments are common in biological cells. DNA, RNA, the cytoskeletal filaments F-actin, microtubules, and intermediate filaments, and polysaccharides such as hyaluronan that form the pericellular matrix all have large net negative charge densities distributed over their surfaces. Several filamentous viruses with diameters and stiffnesses similar to those of cytoskeletal polymers also have similar negative charge densities. Extracellular protein filaments such collagen, fibrin and elastin, in contrast, have notably smaller charge densities and do not behave as highly charged polyelectrolytes in solution. This review summarizes data that demonstrate generic counterion-…
Über Umsetzungen an Poly-p-lithiumstyrol 2. Mitt. Derivate des poly-p-vinyl-di- und Triphenylmethans
1959
Das kurzlich von uns beschriebene Poly-p-lithiumstyrol stellt eine sehr reaktionsfahige makromolekulare metallorganische Verbindung dar. Es wird uber einige Umsetzungen mit Carbonylverbindungen berichtet. Die Reaktion mit Benzaldehyd und einigen p-substituierten Benzaldehyden fuhrt mit hohen Umsetzungsgraden zu Polyvinyldiphenylmethylcarbinolen. Die Reaktion mit Benzophenon liefert Polyvinyltriphenylmethylcarbinol. Diese Verbindung ist in konz. Schwefelsaure loslich als polymeres Analogon des Triphenylmethylkations, was aus der Untersuchung der Absorptionsspektren folgt. Mit MICHLERS Keton last sich ein polymeres Derivat des Malachitgruns darstellen, dessen spektroskopische, Untersuchung in…