Olga Demchenko

Poly(vinyl alcohol)-Graft-Polyacrylamide with Different Grafts Number and Length as Studied by 1H NMR Spectroscopy

ABSTRACT The influence of poly(vinyl alcohol) matrix on stereoregularity of replica polyacrylamide chains in matrix radical graft copolymerization process when varying the grafts number and molecular weight is studied by high-resolution NMR spectroscopy. It was ascertained that the microstructure of formed polymer at homopolymerization and matrix copolymerization processes are not differed. 1H NMR spectroscopy suggests a few contacts of graft chains with the main chain through H-bonding in intramolecular polymer-polymer complex forming in macromolecules of investigated poly(vinyl alcohol)-to-polyacrylamide graft copolymer.

The peculiarities of sorbtion mechanism of phenole molecules by films of PVA-PAAN interpolymer complex

The peculiarities of sorption mechanism of phenole molecules by poly(vinylalcohol) and poly(acrylamide) (PVA-PAA N ) films are examined. An analytical model of absorption process based on diffusive character of penetration of phenole molecules in polymer film with the following spontaneous capturing by selftuning traps is proposed. The analytical results can be easy compared with experimental data obtained by spectrophotometry method. The comparison of theory and experiment gives the average value of resulting diffusion lenght of phenole molecule during «free» life-time ∼10 -6 cm.

Investigation of Inhibiting Action Mechanism of Succinimidophenylmethacrylate Derivatives Prepared by the Diels–alder Reaction on Polystyrene Decomposition

The influence of succinimidophenylmethacrylate derivatives on the polystyrene thermal stability in argon is assessed by dynamic thermogravimetric analysis. The monomers (1 or 3 mol%) prepared by Diels--Alder reaction have been introduced into polystyrene by means of the copolymerization reaction. The decomposition products of polystyrene with additions have been investigated by thermal desorption analysis coupled with mass spectrometry. During the heating of polystyrene with additions, the retro-Diels--Alder reaction produces dienes and dienophiles which react with macroradicals and thus inhibit the radical chain process of polymer thermal decomposition. The inhibiting effect of the succinimidophenylmethacrylate derivatives is determined by the temperature range of the retro-Diels--Alder reaction.

About the compatibility of polymer components in polymer complexes based on poly(acrylamide) and poly(vinyl alcohol)

The issue of applying the usual concepts of polymer compatibility to nonstoichiometric PVA/PAA mixtures of chemically complementary poly(vinyl alcohol) and poly(acrylamide), which form in water solution InterPC (intermolecular polymer complex) stabilyzed by H-bonds, and PAA to PVA graft copolymers (PVA-PAA N ) with different grafted chains number N, that are IntraPC (intramolecular polymer complexes) is discussed. PVA and PAA are compatible on molecular level. At the same time PVA/PAA mixture (50/50 W/W) is characterized by heterogeneous structure consists of InterPC with φ char =9g PVA /g PAA and the excess of unconnected PAA. In the case of IntraPC, yet, only PVA-PAA N , where N=25, is characterized by a single glass transition temperature (Tg). At larger values of N separate PAA domains form giving rise to the corresponding Tg. These results are discussed in view of IntraPC structure peculiarities as a function of N investigated by IR spectroscopy.

Polyacrylamide-Grafted Silica for Environmental Protection

The effect of grafts length on flocculation effectiveness of PAA-grafted silica for kaolin suspension (R = 6.5 μm, C = 30 kg·m−3) comparing with PAA and commercial flocculant Magnafloc LT-27 have been studied. It has been ascertained that nanocomposite with longer grafts is markedly better flocculant. The results of treatments of PAA-grafted silica which have been performed on the waterworks together with different nonionic (A227), anionic (A1020, A1050) and cationic (DB45SSH, KP555) commercial flocculants known in Ukraine are considered. It is shown that PAA-grafted silica alone removes up to 37% and in pair with coagulant up to 75% of pesticide during water clearing.

Compacting of poly(acrylamide)-poly(vinyl alcohol) grafted copolymers in aqueous solution of phenol and its effect in the copolymers films structure

The interaction of phenol with graft copolymers of poly(acrylamide) to poly(vinyl alcohol) (PVA-PAA N ) forming intramolecular polycomplexes (Intra PC), and also with PAA, is investigated by the methods of gel chromatography, viscometry, UV and IR spectroscopy. It is shown, that phenol connection with polymers is weak and carried out on the equilibrium mechanism. Under phenol influence the effect of compacting of polymer macromolecules is observed. It is revealed, in particular, by change of the ratio between different H-bonds structures in polymer films obtained at phenol presence. PVA-PAA N connect phenol more effectively, than PAA; the quantity of bound phenol grows with N.

Reversible structure destruction of intramolecular polycomplexes formed by poly(acrylamide) and poly(vinyl alcohol), under hydrodynamic shear flow

A set of rheologic and thermodynamic researches of diluted and semi-diluted aqueous solutions of poly(acrylamide) to poly(vinyl alcohol) grafted copolymers (PVA-PAA N ) forming intramolecular polycomplexes (Intra PC) by the methods of static light scattering, interferometry and rheology (for gradients of shear rate j≤1312 s -1 ) was carried out. It is established, that the thermodynamic water quality towards the copolymers improves, when the quantity N of grafts increases, but on the whole it remains close to 0-solvent. In PVA-PAA N solutions under action of a hydrodynamic shear field two level of reversible structure destruction are shown. The first level is destruction of network of pinnings and the second one is destruction of Intra PC structure together with destroying of primary associates of copolymer macromolecules. It is shown, that the character of destruction (gradual or uneven) and its depth depend on intensity of the hydrodynamic shear field action, concentration of solution and also copolymer structure. Possible reason of reversibility of PVA-PAA N structure destruction in strong hydrodynamic fields is pointed out.

Synthesis and investigation of bromine containing oxy- and propionoxyphenylimides for polymers thermostabilization

ABSTRACT The new bromine containing oxyphenylimides are synthesized by Diels-Alder condensation from commercial products. From the bromine containing oxyphenylimides were obtained corresponding imidophenylpropionates. The brominating of oxyphenylimides has different influence on their thermal properties subject to diene building. The possible routes of thermal decomposition of the brominated oxyphenylimides and imidophenylpropionates were studied with the help of thermal desorption analysis coupled with mass spectrometry. The perspectives of bromine containing oxyphenylimides usage for creation of new polystyrene stabilizing systems are discussed.

Brominating of Oxyphenylimides for Enhancement of Stabilizing Properties of their Derivatives

New bromine-containing oxyphenylimides are synthesized by the Diels–Alder condensation from commercial products. The effect of the bromination of oxyphenylimides on their thermal behavior as comparing with the thermal stability of polystyrene in air is assessed by dynamic thermogravimetric analysis and differential scanning calorimetry. The bromination of oxyphenylimides has different influences on their thermal properties subject to the diene building. The perspectives of the usage of bromine-containing oxyphenylimides for the creation of new polystyrene-stabilizing systems are discussed.

The PVA-PAAN intrapolymer complexes as sensors with optical response

Sorption of some impurities from aqueous solutions by polymer complex poly(vinylalcohol) with poly(acrylamide) grafted copolymers (PVA-PAAN) was studied by means of spectrophotometry and steady-state fluorescence methods. The experiments showed that the PVA-PAA N films effectively sorbs impurities molecules of average benzene ring from water. Simultaneously, the processes of polymer films dissolving in water take place. The thermal annealing (with the help of special methods) PVA-PAA N film gives a possibility to obtain non-dissolving polymer films which possess high sorbtion ability. Such films are proposed to be used as the sensors with optical response.