Acrylamide In Solution Research Articles

Photoinduced Electron Transfer Polymerization. 4. 4-Carboxybenzophenone−Sulfur-Containing Carboxylic Acids Photoredox Pairs as a Photoinitiating System for Free-Radical Polymerization

A series of sulfur-containing carboxylic acids (SCCA) was investigated as electron donors in photoinduced free-radical polymerizations, in conjunction with 4-carboxybenzophenone (CB) as sensitizer. These carboxylic acids included (phenylthio)acetic acid, S-benzylthioglycolic acid, 4-(methylthio)phenylacetic acid, 2-(methylthio)ethanoic acid, 4-(methylthio)benzoic acid, 2,2‘-thiodiethanoic acid, and 3,3‘-thiodipropionic acid. The results were compared to the simplest thioether, dimethyl sulfide. The mechanism of the radicals' formation was established using nanosecond laser flash photolysis and photochemical steady-state measurements of carbon dioxide formation. Photopolymerizations were carried out in aqueous solutions of acrylamide. Several conclusions follow from the experimental data: (1) The rates of polymerization of the CB/SCCA/acrylamide systems are affected by the yields of secondary processes that follow photoinduced electron transfer, e.g. decarboxylation or deprotonation. This is in addition to the reactivity of the free radicals themselves. (2) The highest initiation yield is observed for the system where there is efficient diffusion apart of the radical−ion pairs, followed by efficient decarboxylation. The resulting radicals are localized on carbons adjacent to the sulfur atom. (3) Free radicals with aromatic moieties are better initiators than are the analogous aliphatic radicals. (4) Radicals that retain the carboxylate moiety are inefficient initiators. (5) Photopolymerization of these systems appears to proceed by the conventional mechanism where termination is bimolecular.

Nitrile Hydratase of Rhodococcus: Optimization of Synthesis in Cells and Industrial Applications for Acrylamide Production

Strain Rhodococcus rhodochrous M8 exhibiting high nitrile hydratase (NHase) activity is a promising catalyst for commercial production of acrylamide. With the aim to enhance the biocatalyst activity, regulation of NHase synthesis in this strain has been investigated. The synthesis of NHase and amidase, which also participated in nitriles metabolism in this strain, was induced by isobutyronitrile, acetamide, or urea. At the same time, the addition of glucose, fructose (rapidly metabolizable carbon sources), or ammonium ions to a medium decreased NHase and amidase synthesis. Using Northern blot analysis we demonstrated that these compounds control the expression of NHase at the transcriptional level. The observed effects of glucose and fructose are not related to the decrease in the intracellular concentration of inducer (acetamide), since these compounds cause neither repression nor inhibition of an inducible active system of acetamide uptake The synthesis of NHase in R. rhodochrous M8 is proposed to be subjected to different regulatory circuits, i.e., in duction, carbon, and nitrogen catabolite regulation, operating at the transcription level. We have optimized the growth conditions for R. rhodochrous M8 on the basis of the obtained data. Application of the improved biocatalyst for acrylamide production allows us to obtain the concentrated (38%) solution of acrylamide.

The inverse emulsion polymerization of acrylamide using poly(methyl methacrylate)-graft-polyoxyethylene as the stabilizer

Inverse emulsion polymerization of an aqueous solution of acrylamide (AM) in toluene is carried out using poly(methyl methacrylate)-graft-polyoxyethylene (PMMA-g-PEO) as an emulsifier. The kinetics of polymerization, morphology of the particle, and particle size of the inverse emulsion have been investigated. The rates of polymerization are found to be proportional to the initiator concentration, the monomer concentration, and the emulsifier concentration. The morphology of particles shows a spherical structure. The mechanism of inverse emulsion polymerization using amphipathic graft copolymer as the emulsifier is proposed. The resulting molecular weights of polyacrylamide are extremely high, and relate to the amphipathic graft copolymer structure. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 528–534, 2001

Surface modification of polymers VII.: Photochemical grafting of acrylamide and N-isopropylacrylamide onto polyethylene initiated by anthraquinone-2-sulfonate adsorbed at the surface of the polymer

Photoinitiators anthraquinone-2-sulfonate sodium salt and (4-benzoyl benzyl) trimethylammonium chloride both adsorb from aqueous solutions at the surface of polyethylene and desorb partly in the presence of water. After adsorption of either photoinitiator on polyethylene, surface grafting occurs easily when the polymer, in contact with a thin layer of acrylamide solution, is irradiated at 350 nm. As a consequence of the grafting mechanism, homopolymer is always formed as by-product. Of both photoinitiators anthraquinone-2-sulfonate is the most suitable because it adsorb more strongly and has a higher absorption coefficient in the near UV. Grafting of acrylamide results in a decrease of the contact angle of the polymer surface with a water droplet from 80 to 25°. After grafting of N-isopropyl acrylamide the contact angle measured at room temperature also drops to 25° but remains 80° when measured at 40°C, i.e. above the L.C.S.T. of the grafted polymer.

Surface modification of polymers VI. Thermal and radiochemical grafting of acrylamide on polyethylene and polystyrene

The surface of polyethylene and polystyrene samples has been made hydrophilic by extension and improvement of a two step method. The polymer surface is first hydroxylated by treatment with an aqueous sodium persulfate solution or by gamma irradiation in water. Afterwards grafting is initiated by the thermal decomposition of hydroxyl groups formed at the surface. In some conditions hydroperoxides can also initiate the grafting. Gamma irradiation of the polymers in the presence of a concentrated aqueous solution of acrylamide results in surface modification of polyethylene but not of polystyrene.

Pressure influences upon shear thickening of poly(acrylamide) solutions

This paper provides experimental data, measured with a Bohlin VOR viscometer and a Haake Searle-type high temperature and high pressure viscometer, which describe the shear thickening behaviour of a poly(acrylamide) in various glycerol-water mixtures. The influence of the glycerol content, the polymer solute concentration, the presence of salts and also the variation of the temperature and the pressure upon the shear thickening properties and associated descriptive parameters are reported. A proposed mechanism for the observed shear thickening behaviour, due to the formation of transient networks between the oriented and stretched polymer chains, under the action of the high shear forces is tentatively presented. The influence of the above variables upon the formation of a proposed interconnected network is discussed and the influence upon the rheological response is considered.

The inverse emulsion polymerization of acrylamide using polystyrene-graft-polyoxyethylene as the stabilizer

Inverse emulsion polymerization of aqueous solution of acrylamide (AM) in toluene is carried out using polystyrene-graft-polyoxyethylene (PSt-g-PEO) as an emulsifier. The kinetics of polymerization, morphology of the particle, and particle size of the inverse emulsion have been investigated. The rates of polymerization are found to be proportional to the initiator concentration, the monomer concentration, and the emulsifier concentration. The morphology of the particle shows a spherical structure. The effects of amphipathic graft copolymer structure on the average molecular weight of polyacrylamide are studied. The mechanism of the inverse emulsion polymerization using amphipathic graft copolymer as emulsifier is proposed. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 2719–2725, 1999

Analysis of Residual Acrylamide In Field Crops

Polyacrylamide (PAM) is a widely used product for a large number of applications. Many of the emerging applications are in the area of agriculture. PAM is blended with pesticides as a thickening agent, added to irrigation water to minimize soil erosion, and used as a medium for hydroponically grown crops. Although PAM is stable and considered to be safe, residual acrylamide (AMD) monomer is a neurotoxin and animal carcinogen. In this work, residual AMD is analyzed in a variety of crops that were grown under PAM treatment to stabilize soil erosion. Corn, potatoes, sugar beets, and beans are analyzed for AMD. A sample of the crop is homogenized with water, and the water layer is filtered and derivatized with bromine to form 2,3-dibromopropionamide. The derivative is then extracted with ethyl acetate and converted to the more stable 2-propenamide prior to gas chromatographic analysis using an electron capture detector. Capillary Carbowax columns were used. All tested crops show < 10 ppb AMD. Furthermore, it seems that AMD is not stable when it comes in contact with the crop tissues. In the presence of plant tissues, AMD will dissapear as a function of time. Beans blended with 100 ppb AMD for 10 min yield a recovery of only 22%. For a bean sample that was soaked with 500 ppb AMD solution for 18 h, the recovery is 7%. Other crops show different AMD recoveries.

The grafting of acrylamide onto poly(?-caprolactone) and poly(1,5-dioxepan-2-one) using electron beam preirradiation. I. Influence of dose and Mohr's salt for the grafting onto poly(?-caprolactone)

Poly(ε-caprolactone) films (TONE® 787) were irradiated by electron beam in air prior to grafting in aqueous solutions of acrylamide. The grafting kinetics and molecular weight of the grafted poly(acrylamide) chains were studied with irradiation doses between 2.5 and 20 Mrad and in the Mohr's salt concentration range of 0.0025–1 wt %. The grafting rate and yield were strongly dependent on the Mohr's salt concentration. By molecular weight analysis of grafted poly(acrylamide) chains, it was shown that the molecular weight is approximately proportional to the mass of the grafted PAAm. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 1643–1649, 1999

Polymerization of acrylamide in solution and inverse emulsion: number molecular weight distribution with chain transfer agent

The molecular weight distributions of the free-radical polymerization of acrylamide in solution and in inverse emulsion are examined as a function of concentrations of initiator and of amount of added chain transfer agent (sodium formate). When these distributions are displayed as ln(number molecular weight distribution), readily obtained from the GPC trace (essentially by dividing by the square of molecular weight), the results can be semi-quantitatively interpreted in terms of the amounts of chain stoppage by transfer and by termination.

SUPER ABSORBENT HYDROGELS: INTERPENETRATING NETWORKS OF POLY(ACRYLAMIDE-co-ACRYLIC ACID) AND POLY (VINYL ALCOHOL): SWELLING BEHAVIOR AND STRUCTURAL PARAMETERS1*

A series of semi- and full interpenetrating networks (IPNs) of poly(acrylamide-co-acrylic acid) and poly(vinyl alcohol) were synthesized by polymerizing an aqueous solution of acrylamide, acrylic acid and N,N/-methylenebis(acrylamide) in the presence of poly(vinyl alcohol) (PVA). PVA was crosslinked with glutar-aldehyde in a subsequent step. The swelling behavior of the IPNs were monitored as a function of composition of the IPNs, extent of crosslinking of PVA, pH and ionic strength of the swelling medium. Incorporation of acrylic acid raises the swelling ratio several fold while crosslinking of PVA suppresses it. The IPNs being ionic, swelling is affected by the pH and ionic strength of the medium. The basic structural parameter of the gel network Mc, the crosslink dimension was calculated using the Flory-Rehner equation. The swelling can be effectively varied by adjusting acrylic acid content and extent of crosslinking of PVA. *IICT Communication number 4096

Electrochemical polymerization of pyrrole in acrylamide solution

Electrochemical polymerization of pyrrole (Py) in an excess of acrylamide (AAm) was accomplished by using an acetonitrile–tetraethyl ammonium perchlorate (TEAPC) solution containing both monomers. Characterization of soluble and insoluble products was carried out via FT-IR spectrum, cyclic voltammogram (CV), UV–visible spectrum, scanning electron microscope (SEM), differential scanning calorimetry (DSC) and elemental analysis. The role of monomer concentrations on the formation of resulting polymer was investigated. Since the polymerization rate of Py is faster than that of AAm, the appropriate ratio of concentrations of monomers have chosen to have chance to interact AAm with Py oligomers which was formed immediately on the electrode surface. Inclusion of AAm to polymer and the mole ratio of resulting product was reported.

An experimental investigation of negative wakes behind spheres settling in a shear-thinning viscoelastic fluid

We present detailed ex- perimental results examining "neg- ative wakes" behind spheres settling along the centerline of a tube con- taining a viscoelastic aqueous poly- acrylamide solution. Negative wakes are found for all Deborah numbers (2.43 ≤ De(c ˙ ) ≤ 8.75) and sphere-to- tube aspect ratios (0.060 ≤ a/R≤ 0.396) examined. The wake structures are investigated using laser-Doppler velocimetry (LDV) to examine the centerline fluid velocity around the sphere and digital particle image velocimetry (DPIV) for full-field velocity profiles. For a fixed aspect

Advantages of synthetic multi-element reference material with pseudo-biological matrix in activation analysis

A new type of synthetic multi-element reference material (SyRM) with pseudo-biological matrix was prepared by a co-polymerization reaction of an aqueous solution of acrylamide and acrylic acid containing known amounts of the elements. SyRM has the excellent homogeneity and the quantitative retention of major and trace elements. Elemental composition can simulate the biological samples to be analyzed. SyRM can be used for the same purpose of conventional certified reference materials with high accuracy and precision. SyRM was applied as a comparative standard for non-destructive photon and α-particle activation analysis. Selective preconcentration methods combined with NAA were proposed and the SyRM containing about fifty elements with known amounts was prepared. In order to evaluate the reliability of present methods, 3d transition elements and rare earth elements were determined in the SyRM. It was clearly observed that these methods have good accuracy and precision in trace analysis of biological materials by comparing the analytical results with the original contents in the SyRM. The SyRM supported multielement analysis of marine macro-algae can be used as comparative standards for the quality assurance of analytical techniques.

Using acrylamide and oligo (oxyethylene) methacrylate in corrosion protection of steel

This study examines the use of radical polymerization in a solution of acrylamide (AA) and oligo(oxyethylene) methacrylate (OEGMA) for corrosion and dissolution protection of steel in aerated aqueous solutions. The inhibiting efficiency of the different additives is evaluated from anodic and cathodic polarization curves as well as from polarization resistance. The corrosion protection is determined under varied medium composition and surface pretreatment conditions. The temperature effect is also studied and the thermodynamic activation parameters of the corrosion reaction are obtained. It was found that the examined compounds can afford good protection, even to an already oxidized steel surface, particularly in highly acidic solutions. At moderately elevated temperature, OEGMA provides higher inhibition efficiency compared to AA and the corrosion reaction was found to be entropy controlled.

The inverse emulsion polymerization of acrylamide with pentaerythritolmyristate as emulsifier. 2. Mathematical modelling

A mathematical model of the inverse emulsion polymerization of aqueous acrylamide solutions in isooctane as dispersing media with the chemically pure emulsifier pentaerythritolmonomyristate and an oil-soluble azo initiator has been developed. A Monte Carlo method was used successfully to calculate the kinetics, molar mass averages and average particle sizes. The computation time of the method was reduced by calculating the chain length of the polymer molecules via the life-time of the radicals. It is shown that a few assumptions based on the mirror image of an ideal conventional emulsion polymerization with Smith-Ewart case 2 kinetics are sufficient to comprehensively describe the experimental findings.

The inverse emulsion polymerization of acrylamide with pentaerythritolmyristate as emulsifier. 1. Experimental studies

The inverse emulsion polymerization of aqueous acrylamide solutions in isooctane as dispersing media with the emulsifier pentaerythritolmyristate and an oil-soluble azo initiator was studied, particularly with respect to the influence of the chemically pure emulsifier. In this free radical polymerization, a water-in-oil emulsion with droplet sizes around 10μm is converted into a latex with average particle diameters between 80 and 200nm containing a polymer with molar masses up to 16×106gmol-1 Kinetic data were measured by adiabatic as well as by isothermal calorimetry. The influences of various parameters on polymerization kinetics, particle numbers and molar mass averages were studied. Experimental results show a positive influence of the emulsifier concentration on the reaction rate and indicate the dominance of a bimolecular termination re-action with respect to the polymer radicals above a certain initiator concentration. © 1998 SCI.

Thermoresponsive Opalescence ofN-Isopropylacrylamide/N,N‘-Methylene(bis)acrylamide Copolymer Gel

Polymer gels with various degrees of opacity were first made by copolymerization of N-isopropylacrylamide/N,N‘-methylene(bis)acrylamide solutions at polymerization temperatures of 22−29 °C. The opaque gels underwent a gradual opacity change from transparent to a whitish state with increase in temperature, whereas transparent gels prepared at polymerization temperatures below 21 °C underwent a discontinuous opacity change from transparent to white at 32 °C. These results could be successfully explained by taking into account a microaggregate structure formed by hydrophobic side chains of the gel polymers, in addition to conventional three-dimensional network structure. In particular, the results of temperature-dependent opacity changes of the gels were consistently accounted for by increasing/decreasing of the microaggregate structure upon change in temperature. From the other point of view, such a novel structural changes could be regarded as a sort of microphase separation formed between the hydrophobic ...

Quasi-Ordered Structure in Highly Cross-Linked Poly(acrylamide) Gels

By means of small-angle light scattering and turbidity measurements, we have studied the growth of highly cross-linked poly(acrylamide) gels, and show that they are endowed with a quasi-ordered structure. A peak at finite angle in the scattering profiles is observed, revealing the presence of a characteristic length scale in the range of a few micrometers. This length is larger for higher cross-linker content. The role of aggregation of the bis(acrylamide) cross-linker in determining the final structure of the gel is investigated by studying the polymerization of a pure bis(acrylamide) solution. The time evolution of the turbidity of the gels and the scattering profiles of the bis(acrylamide) solution suggest that cross-linker aggregation leads to two-phase separation. However, this process is arrested at a microscopic scale by the onset of gelation. The resulting structure is characterized by larger pores than in gels at standard cross-linker concentration, as can be seen from electrophoretic migration o...

THE EFFECT OF SLNGLE AND MIXED MICELLES OF SURFACTANTS ON POLYMERIZATION OF ACRYLAMIDE

ABSTRACT Acrylamide is conveniendy polymerized in aqueous solution lo a water soluble polymer. The measurements of kinetic parameters of polymerization of acrylamide, in aqueous and micellar solution, have been earned out by conduction calorimeter. The polymerization is initiated by sodium sulfite and sulfite-persulfate redox system. The effect of initiator and monomer concentration as well as temperature and surfactants on polymerization rale constant has been investigated. The analog thermogram method has been employed to calculate the rate constants. The activation energy is calculated from Arrhenius relationship and molecular weights are determined by viscometry. Rate equations have been derived and reaction mechanism hove been suggested. The rate of reaction is found to increase with temperature and monomer concentration.