Amphoteric Polyelectrolyte Research Articles

Apparent antihaemophilic activity of basic amphoteric polyelectrolytes.

Amphoteric polyelectrolytes with alkaline isoelectric points (for example Ampholine 9-11) intended for use in isoelectric focussing were found to shorten the prolonged partial thrombosplastin clotting time with kaolin (PTTK) of plasma deficient in factor VIII. The response of this PTTK to Ampholine 9-11 was linear when plotted on double log paper with a slope slightly greater than that of factor VIII itself. Ampholine 9-11 at 2% concentration had factor VIII and factor IX activity equal to that of normal plasma as well as somewhat less activity as factor XI. It had no significant correcting effect on the clotting of plasmas deficient in factors V, VII, X, II OR XII. Ampholine 9-11 inhibited low concentrations of contact activators and its effect in correcting factor VIII deficient plasma was found to be related to the degree of contact activation.

The adiabatic compressibility of polyelectrolytes: Sodium and hydrochloride salts of acrylic acid–N-dimethylaminoethyl methacrylate copolymer

The results of adiabatic compressibility measurement for the 100% neutralized sodium and hydrochloride salts of three copolymers of acrylic acid and N-dimethylaminoethyl methacrylate, namely, AA-DAM 58, AA-DAM 43, and AA-DAM 33, are discussed. Similar to three unneutralized amphoteric polyelectrolytes, the ϕK2 and ϕV2's for these salts are found to be concentration independent. Since in the former both anionic and cationic groups are present, fully neutralized sodium salts and hydrochloride salts of these polyelectrolytes are expected to show a decrease in ϕK2i0 and ϕV2i0 values due to maximum electrostriction. In fact, in case of AA-DAM 58 with excess amino group in the chain (58%), the experimentally obtained values are found to be −9.6 × 10−4 cc/bar/mole and 159.6 cc/mole, and −3.3 × 10−4 cc/bar/mole and 164.4 cc/mole for sodium and hydrochloride salts, respectively, which corresponds to a decrease of 7.1 × 10−4 cc/bar/mole and 4.9 cc/mole for the sodium salt and 0.8 × 10−4 cc/bar/mole and 0.1 cc/mole for the hydrochloride salt. In contrast, the hydrochloride salt of AA-DAM 43 shows an increase of 6.2 × 10−4 cc/bar/mole and 2.2 cc/mole, respectively, while in case of AA-DAM 33, both the hydrochloride salt (56.2 × 10−4 cc/bar/mole and 24.7 cc/mole) and the sodium salt (6.2 × 10−4 cc/bar/mole and 6.2 cc/mole) show an increase. This increase has been ascribed to suppression of dissociation of carboxyl groups by the hydrochloric acid (common ion effect) added for neutralization. However, in all the three amphoteric copolymers, when neutralized with NaOH solution or HCI acid, the viscosity increases over that of the unneutralized copolymer.

The influence of amphoteric polyelectrolyte gelatin on the formation of Cobalt(II), Nickel(II), Magnesium(II), Manganese(II), Iron(III) and Aluminium(III) hydroxide)

The influence of amphoteric polyelectrolyte on the formation of some sparingly soluble hydroxides was investigated in the system: gelatin-Mez+-NaCI-HCI or NaOH, where Co2+, Ni+, Mg2+, Mn2+, Fe3+, A13+ in the form of their soluble salts were taken for Mez+.

Adiabatic compressibility of some amphoteric polyelectrolytes

The results of adiabatic compressibility measurements for two amphoteric polyelectrolytes, acrylic acid–4-vinyl-N-n-butylpyridinium bromide copolymer and methacrylic acid–4-vinyl-N-n-butylpyridinium bromide copolymer, and their completely neutralized potassium salts have been described. The two amphoteric polyelectrolytes are strongly acidic, and the strength of the acidic group has been increased by the presence of the neighboring basic group. The reduced viscosity for these polyampholytes is extremely low (∼0.03–0.07 dl/g) which may be on account of the mutual interaction of acid and base groups making the polyelectrolyte chain highly coiled and compact. The apparent molal volume ΦV2 and apparent molal compressibility ΦK2 are concentration independent. Their potassium salts showed the lowest ΦV2 and ΦK2 values as the electrostriction is highest here; these values showed a slight increase in the presence of dilute KBr solution as the dissociation is somewhat reduced. However, in excess KBr solution, the acrylic acid-containing copolymer having comparatively more carboxyl groups (21.7%) behaves more or less similar to poly(acrylic acid), whereas the methacrylic acid-containing copolymer, with only 15.1% carboxyl groups, behaves closely to poly(4-vinyl-N-n-butylpyridinium bromide). These polyelectrolytes showed absorption in the 2700 to 3800 Å region in the presence of chloride, bromide, and iodide ions which are due to charge transfer complex formation between the halide ions and the polymer nucleus. The magnitude of extinction coefficient for these two polyampholytes is much less than that of poly(4-vinyl-N-n-butylpyridinium bromide). The limiting values of apparent molal volume, ΦV20, for acrylic acid- and methacrylic acid-containing copolymers are 183.9 and 184.6 cc/mole, respectively. These experimentally determined values fall short of 9.2 and 6.2 cc/mole compared to the calculated values (if there was no interaction between acid and base groups) which are definitely due to mutual interaction of acid and base groups in the polymer chain.

Flow birefringence of aqueous solutions of copolymers of methacrylic acid with 2-methyl-5-vinylpyridine

The investigation of the Maxwell effect on polyacids and polybases in earlier work [1–3] had shwn that the polyelectrolytic swelling of the polyion was accompanied by an increase of the equilibrial rigidity of chains and a molecular change from the flexible chain conformation of the polymer to a semi-rigid one. A similar study using polyampholyte solutions possessing molecules with cationic and anionic groups was therefore of interest. Although a considerable number of studies exists on amphoteric polyelectrolytes [4–7], little is known about the hydrodynamic, and especially the optical properties of these. This paper describes some of the experimental findings on the optical anisotropy and viscosity of polyampholyte solution to clarify the effect of pH and of ionic strength on the conformational properties of their molecules.

Salt-induced contraction of bacterial cell walls.

Intact Bacillus megaterium cells were found to contract as much as 26% in terms of dextran-impermeable volume when transferred from water to unbuffered, non-plasmolyzing NaCl solutions. This shrinkage appeared to be primarily due to electrostatic wall contraction rather than to any osmotic response of the cells. A variety of salts (but not sucrose) added to water suspensions of isolated cell walls caused protons to be released from the walls with resultant lowering of suspension pH and contraction of the structures. In effect, B. megaterium walls behaved as flexible, amphoteric polyelectrolytes, and their compactness in aqueous suspensions was affected by changes in environmental ionic strength and pH. Isolated walls were most compact in low ionic strength media with a pH of about 4, a value close to the apparent isoelectric pH of wall peptidoglycan. Electrostatic attractions appeared to play a major role in determining the compactness of highly contracted walls, and the walls responded to increased environmental ionic strength by expanding. In contrast, electrostatic repulsions were dominant in highly expanded walls, and increased environmental ionic strength induced wall contraction. Walls of whole bacteria also shrank when the cells were plasmolyzed. This second type of contraction seemed to result from relief of wall tension during plasmolysis, and it could be induced with nonionic solutes. Thus, cell wall tone in B. megaterium appeared to be set both by mechanical tension and by electrostatic interactions among wall ions.

Studies on the Water-Soluble Polymers. XIII

Copolymerization of 2-methyl-N-vinyl imidazole (MVI) with itaconic acid (IA) and methyl acrylate (MA) were studied.MVI was copolymerized with IA in water at 70°C, using potassium persulfate as an initiator, and MVI was copolymerized with MA in dioxane at the same temperature using benzoyl peroxide as an initiator. In the copolymerization of MVI with IA, the maximum conversion was obtained when equal moles of the monomers were reacted. In the copolymerization of MVI with MA, the conversion was found to increase with the molar ratio of MA to MVI in the monomer mixture. The monomer reactivity ratios in the copolymerizations were determined as follows : for MVI (1) - IA (2) r1=0.17, r2=1.02 for MVI (1) -MA (2) r1=1.28, r2=0.05 The properties of the resulting copolymers were investigated, and MVI-IA copolymer and alkalinehydrolyzed MVI-MA copolymer were found to serve as amphoteric polyelectrolytes.

Studies on the Water-Soluble Polymers. VI

Polyethyleneimine was found to be combined with partially hydrolyzed polyacrylamide in aqueous solution to give a high molecular complex compound. The complex compound having many imino and carboxylate groups indicated the properties of amphoteric polyelectrolyte. The cationic and anionic properties of the complex compound were found to depend upon the combining ratio, molecular weight and hydrolyzing degree of the components and hydrogen ion concentration of the solution. Each obtainable compound came to present higher anionic properties in proportion to the hydrolyzing degree of polyacrylamide, or oin inverse proportion to the mixing ratio of polyethyleneimine and the hydrogen ion concentration of its solution : while it shew as much cationic properties, providing these constitutent ratios counterwork. Balancing of the strength of both cationic and anionic groups in the compound minimized the solubility of the compound and the solution of certain concentration became turbid by precipitation. The turbid solution could recover the former clearity by adding acid or alkali into the solution or by heating.It was found that the complex polyelectolyte is a very excellent flocculating agent. The flocculating capability was far superior to that of polyethyleneimine or polyacrylamide alone, because the polyelectrolyte has very high molecular weight and enormous number of ionic groups. In suspension of clay or fine pulp fibers, for example, the complex compound adsorbed readily at the surface of the suspending particles of every sizes, and flocculation occured through decreasing of zeta potential of particles and interparticle bridging by macromolecular chains. In paper making, the addition of the complex polyelectrolyte into pulp suspension in beating process gave excellent effect on sizing and strength of the paper made up. The application of the compound was effective even in the paper making in which aluminium sulfate is limited to use. The flocculating effect was also found to utilize to clarify white water that is waste water in paper making industry.

Preparation and titration of amphoteric polyelectrolytes

AbstractA series of amphoteric polyelectrolytes have been made by copolymerizing N‐dialkylaminoethyl acrylates and methacrylates with acrylic, methacrylic, or itaconic acids in unbuffered aqueous solutions or in nonaqueous solutions at 70°C. using potassium persulfate or azobisisobutyronitrile as the catalyst. The purified copolymers were titrated electrometrically on a semimicro scale. The composition of the copolymers as obtained by titration agreed with calculations based on the analysis of nitrogen content. Except for itaconic acid copolymers, the titration curves exhibited separate and nonoverlapping ionization regions for the acid and basic components and allowed the assessment of the pK values of the acid and amine groups and also the pI values of the copolymers. The pK and pI values varied with the composition of the copolymers in the expected manner. As the frequency of a given group along the main chain increased, its apparent strength decreased. The pI values also shifted to lower pH values as the number fraction of acid groups increased. All these effects could be explained on the basis of the theory of the electrical free energy of ionization. The pI values computed graphically agreed within experimental error with those calculated from the equation: where α is the degree of ionization of the group present in excess in the polyelectrolyte. The implication is that the electrical free energy of ionization does not appear to vanish at the iso‐electric point.