Ye.F. Razvodovskii

The formation of amide linkages in polyelectrolyte salt complexes

Abstract The formation of amide linkages in glassy polyelectrolyte complexes of poly-(acrylic acid) (PAA) and poly(methacrylic acid) (PMA) with linear polyethyleneimide, has been investigated by IR spectroscopy. It is shown that the occurrence of the amidization reaction is largely dependent on the structural complementariness of the original polymeric reactants and their packing arrangement in the polyelectrolyte complex. The results of this work indicate a fairly well ordered structure of the polyelectrolyte complexes and of the polyamide products of their chemical reaction.

Polyelectrolyte complexes based on polymeric quaternary ammonium salts

Abstract Potentiometric titration and optical rotatory dispersion were used in a study of the formation of polyelectrolyte complexes of polyacrylic (PAA) and poly- l -glutaminic (PGA) acids with a number of ionenes differing as to charge distribution along the chain. It is shown that the chemical structure of an ionene has a major effect on the way in which reactions between polyelectrolytes take place. In addition it was found that in some of the ionenes the composition of thi polyelectrolyte complexes varies in the initial stages of the reaction. The formation of polyelectrolyte complexes was found to have a considerable effect on the conformation of PGA, and a conformation with optical properties corresponding to a statistical coil conformation becomes the stable conformation of PGA in a complex. For PGA in a complex with ionenes there is considerable displacement of the helix-coil transition into the acid region of pH. This displacement is inversely proportional to distance between ionene groups in the ionene chain.

Structure and properties of polyelectrolyte complexes of polyacrylic acid and polymeric heterocyclic amines

Abstract A study has been made of acid-base properties of heterocyclic polymeric bases (polyethylene piperazine and polyethylene piperidine) and features of their interaction with polymeric acids have been investigated. It is shown that the ionization constants of the polymeric bases are significantly lower than those of their low molecular weight analogues. It was found that one nitrogen atom in the piperazine ring does not take part in complexation with polyacrylic acid, with the result that the polyelectrolyte complexes formed contain many free units of polyacrylic acid. The state of ionization of these units determines the phase state of the polyelectrolyte complexes. The properties of their gels in various media are shown to depend on the state of ionization of carboxyl groups that have not been incorporated into the system of interchain salt bonds. The behaviour of the gels in media with pH > 6·5 depends on the electrostatic repulsion of ionized free carboxyl groups of polyacrylic acid.

Kinetics of radical polymerization of 1-vinyl-1,2,4-triazole☆

Abstract Studies were made of kinetic features of radical polymerization of 1-vinyl-1,2,4-triazole and the molecular weight variation of poly-1-vinyl-1,2,4-triazole in water, in DMF and in DMAA. The rate of polymerization of the monomer in water and MW of the polymer obtained is higher than in other solvents. MW of poly-1-vinyl-1,2,4-triazole is proportional to the concentration of the monomer. It was shown that a typical feature of polymerization, which is general for all the solvents studied, is the existence of a reaction rate for the initiator with a reaction order higher than 0·5. The mechanism of monomolecular decay of macroradicals is discussed. The effective activation energy of polymerization was found.

Conditions of formation and properties of membranes of polyelectrolyte complexes prepared using weak polyelectrolytes

Abstract A method is proposed for obtaining semi-permeable membranes swelling in water from solutions of weak polyelectrolyte complexes. Volatile, weak low molecular weight acids and bases were selected as solvents. Membrane formation depends to a large extent on the choice of solvent. It was found that in the equilibrium swollen state in water the membranes obtained are gels of polyelectrolyte complexes which are stable in wide range of pH values (pH 2–8). A study was made of the permeability of membranes prepared using polyelectrolyte complexes based on polyacrylic acid and polyethylene piperazine in water and urea.

Synthesis and properties of poly-β-[N,N-dimethyl-N-(β-methacryloxyethyl)]-propiobetain☆

Abstract β-[N,N-dimethyl-N-(β-methacryloxyethyl)]-propiobetain was synthesized by reacting dimethylaminoethyl methacrylate (DMAEMA) with β-propiolactone and the product was used to produce polybetain (PB). Infrared and nuclear magnetic resonance (NMR) spectroscopies as well as potentiometric methods were used to establish the bipolar nature of the compounds. Like betain, the heating of PB resulted in a rearrangement into the acrylic acid salt and PDMAEMA. The kinetic parameters of this process were evaluated, the electrochemical and hydrodynamic properties of PB examined and some of the characteristics of the PB behaviour (absence of polyelectrolysis capacity, effect of ionic strength on the PB molecular dimensions, absence of the Donnan effect) were made clear; such a behaviour is not normally found with polyelectrolytes.

Polymerization kinetics of bicyclic amines

Abstract The polymerization of the following ring compounds containing nitrogen has been studied in the present work: 1-azabicyclo-(3,1,0)-hexane (ABH), conidine, quinuclidine and triethylenediamine under the action of quaternary ammonium salts (QAS), ammonium salts (AS) and complexes formed between boron trifluoride and the monomers in methanol. It has been shown that polymerization of the ring compounds under the action of those catalysts occurs by a “living” polymer type of polymerization. A mechanism for the polymerization of the monomers is proposed on the basis of the kinetic data. It has been established that the polymerization of the ring compounds containing nitrogen occurs, under the action of QAS, with conditions of rapid initiation, but under the action of AS and the complex with conidine, with conditions of slow initiation.

The synthesis and properties of aliphatic poly-n-oxides☆

Abstract The synthesis and some of the physico-chemical properties of aliphatic poly-N-oxides with the N-oxide groups in the main chain are described. The effects of the oxidation time, the temperature, the amounts of added reagents has been studied and methods developed to determine the oxidation efficiency of the poly-N-oxides, the molecular weights (mol.wt.) and their distribution (MWD). The degradation of the polymers has been studied in model conditions. It was found to have a radical mechanism, and its activation energy was measured.

Investigation of the mechanical properties of membranes of polyelectrolyte complexes based on weak polyelectrolytes

Abstract A study has been made of the mechanical properties of membranes of poly-electrolyte complexes based on polyacrylic acid and polyethelenepiperazine under uniaxial tension in aqueous and aqueous-organic media at different temperatures. It has been shown that the mechanical properties of such materials are determined to a considerable extent by the nature of the medium in which the deformation is carried out, as well as by the proportions of the components in the polyelectrolyte complex. The permeability of the membranes of various compositions have been studied in water and urea. A correlation is found between the mechanical ultrafiltration and dialysis properties of the membranes investigated. Suggestions concerning the structure of such materials are put forward on the basis of the experimental data.

Mechanism of polymerization of ring-compounds containing nitrogen☆

Abstract The detailed mechanism of the polymerization of ring-compounds containing nitrogen, namely, 1-azabicyclo-(3,1,0)-hexane (ABH) conidine, quinuclidine and triethylene diamine has been investigated in the present work under the effect of quaternary ammonium salts, ammonium salts and the BF 3 ·conidine complex. It has been shown that the active sites for the polymerization of the monomers are ions and ion pairs; the activity of ion pairs is comparable with or greater than the activity of the free ions. The effect of the nature of the counter-ion, cation and the polarity of the medium on the reaction rate has been studied. It has been established that the polymerization rate depends on the nature of the counter-ion for polymerization by ion pairs and does not depend on the counter-ion for polymerization by free ions. The reaction rate increases in proportion to the size of the counter-ion for polymerization by ion pairs. The enthalpy changes have been measured for the ring compounds containing nitrogen and these have been correlated with the activation energies.