Acrylamide In Aqueous Solution Research Articles

The construction of white-light-emitting anisotropic hydrogel

In this work, hybrid anisotropic hydrogel is developed through dispersing carbon quantum dots, ultrahigh magnetic nanoparticle-coated alumina (Fe/Al2O3) platelets in acrylamide aqueous solution in the assistance of magnetic field, then fix the oriented structure via gelation. The aligned Fe/Al2O3 platelets result in formation of anisotropic structure, thus endows the hydrogels mechanical anisotropy and fluorescent anisotropy. White-light emission is obtained via varying the weight ratio of yellow-emitting ZnO QDs and blue-emitting N,S-CDs. This strategy not only enriches the mechanical/fluorescent dual anisotropic soft materials, but also have great potential application in the fields of organic light-emitting diodes, nonlinear optics and field effect transistors.

Micro flow photochemical synthesis of Ca-sensitive fluorescent sensor particles.

Fluorescence probes have widely been used for detecting and imaging Ca2+‐enriched parts of cells but more rarely for quantitative determination of concentrations. In this study we show how this can be achieved by a novel approach using hydrogel particles. In a microfluidic co‐flow arrangement spherical droplets were generated from an aqueous solution of acrylamide, N,N'‐methylenebisacrylamide crosslinker and photoinitiator and subsequently photo‐cured in situ yielding gel particles in a sub millimeter range. These particles were separated, dried under reduced pressure and re‐swollen in water containing Rhod‐5N tri potassium salt as calcium ion selective fluorescence probe. After that the particles were dried again and stored for further investigations. Upon exposure of dried particles to calcium chloride solutions they swell and take up Ca2+‐ions forming a strong fluorescing complex with Rhod‐5N. Thus, fluorescence intensity increases with calcium ion concentration. Up to ca. 0.50 mM the enhancement effect is strong and then becomes considerably weaker. The intensity‐concentration‐dependence is well described by an equation derived from the equilibrium of the formation of a 1:1 Ca2+:Rhod‐5N complex. The particles allow for a fast optical determination of Ca2+‐concentrations up to 0.50 mM in analyte volumes down to below 10 μL.

The New Approach to the Preparation of Polyacrylamide-Based Hydrogels: Initiation of Polymerization of Acrylamide with 1,3-Dimethylimidazolium (Phosphonooxy-)Oligosulphanide under Drying Aqueous Solutions.

The new initiator of the polymerization of acrylamide, leading to the formation of crosslinked polyacrylamide, was discovered. The structure of the synthesized polyacrylamide was characterized by XRD, 1H NMR, and 13C NMR spectroscopy. It was shown that 1,3-dimethylimidazolium (phosphonooxy-)oligosulphanide is able to initiate radical polymerization under drying aqueous solutions of acrylamide, even at room temperature. According to XRF data, the synthesized polyacrylamide gel contains 0.28 wt% of sulphur. The formed polymer network has a low crosslinking density and a high equilibrium degree of swelling. The swelling rate of polyacrylamide gel in water corresponds to the first order kinetic equation with the rate constant 6.2 × 10−2 min−1. The initiator is promising for combining acrylamide polymerization with the processes of gel molding and drying.

ОЧИЩЕННЯ АКРИЛАМІДУ ВІД ІНГІБІТОРІВ ПОЛІМЕРИЗАЦІЇ ДЛЯ ВИГОТОВЛЕННЯ ВИСОКОЯКІСНИХ ФЛОКУЛЯНТІВ НА ОСНОВІ ПОЛІАКРИЛАМІДУ

Polyacrylamide and its copolymers are widely used as flocculating agents for the separation of industrial suspensions. The formation of high molecular weight polymers depends on the content of various impurities present in the monomer. The article presents the scientific and practical information on the production of acrylamide by sulfuric acid method of hydration of nitrile acrylic acid in the form of an aqueous solution of different concentrations and a more modern heterogeneously catalytic method of hydration of acrylonitrile using as catalysts with variable valence. Ways to get different impurities in the stages of production of acrylamide with the purpose of applying appropriate methods for its purification. Laboratory studies of the purification of an aqueous solution of acrylamide from iron ions were carried out as an element of inhibition of the premature polymerization process.

Synthesis of ultra‐high concentration of salt‐resistant polyacrylamide

Glucose, an environmentally friendly and renewable material, is modified differently in various fields. In the petrochemical industry, water‐soluble polymer with salt resistance plays an important role in the production in high‐salinity reservoirs. In this work, N,N‐dimethyl ethanolamine was reacted with glucose to synthesis a polymerizable monomer Gf (N,N‐dimethylaminoethylglucoside). Gf was polymerized with acrylamide in aqueous solution to obtain copolymer glucose modified polyacrylamide. The copolymer was characterized by Fourier transform infrared spectroscopy, 1H‐NMRspectroscopy, scanning electron microscopy, and thermogravimetric analysis. The temperature resistance, salt resistance, and shear resistance of the copolymer solution were evaluated. The results shown that the copolymer had excellent salt‐thickening effect, favorable temperature resistance, and shear resistance. We expect that this work would provide a new method for designing polymers with excellent temperature resistance, salt resistance, and shear resistance.

On the possibility of using combined polymerization and drying in synthesis of polyacrylamide

This paper presents investigation results of polyacrylamide synthesis with combined polymerization and drying. First, polyacrylamide synthesis was carried out in concentrated aqueous solutions of acrylamide at 30°C. Polymerization was initiated by K2S2O8/Na2S2O3 an oxidation–reduction system. The monomer conversion degree at this stage did not exceed 80%. Further, polymerization with simultaneous solvent elimination from the prepolymer was carried out in a dryer with infrared heat supply and natural convection. Such conditions provide monomer conversion degree up to 100%.

Assesment of seed quality

A new method for assessing the seed quality of seeds (seed germination) is developed, which involves the germination of seed  material in the cells of a special bed, which is a rectangular block with cells for seeds, made of strong wood or plastic. As a substrate for seed germination, an 8% aqueous solution of acrylamide is used, this is a gel that retains moisture well and replaces moistened sand or filter paper. Using this method makes it possible to increasethe accuracy in calculating the seed rates.

Biomimetic gels with chemical and physical interpenetrating networks

AbstractThis study aimed to create and to characterize the functional properties of gels with semi‐interpenetrating network (semi‐IPN) with focus on possible use of these composites in biomedical engineering. Polyacrylamide as a synthetic biocompatible polymer was chosen for the chemical network. The physical network comprised the gel‐forming polysaccharides xanthan gum or gellan gum. Gels were synthesized by radical polymerization of acrylamide in aqueous solutions of polysaccharides. Mechanical and electrical properties of gels with 0.2, 0.4, 0.6, 0.8 and 1.0 wt% content of polysaccharide were investigated. It was found that the inclusion of a small amount of xanthan or gellan into the polymeric network of a polyacrylamide gel significantly shifts the gel electrical potential towards the rest potential of living cells and Young's modulus towards the elasticity limits of biological soft tissues like non‐activated muscles. From the viewpoint of biomedical applications, the main advantage of the proposed composites is that the semi‐IPN structure provides a nonlinear dependence of gel tension on gel deformation, which mimics the elasticity of natural tissues. This feature opens the possibility for the promising use of the proposed gels for musculoskeletal minibioimplants or scaffolds for tissue engineering. © 2018 Society of Chemical Industry

Real‐time monitoring by proton relaxometry of radical polymerization reactions of acrylamide in aqueous solution

AbstractThe potential of time‐domain nuclear magnetic resonance (TD‐NMR) for the real‐time monitoring of solution radical polymerizations is demonstrated. A model system composed of a redox‐pair initiator system, acrylamide as monomer and water as solvent was investigated. A second‐generation continuous wave free precession technique was employed to measure the longitudinal relaxation time constant (T1) of the samples throughout the polymerization reactions. This parameter was shown to be sensitive to the reactant feed free‐radical enhancement of the water molecule relaxation time, making it a good probe to monitor monomer conversion in real time in an automated, non‐destructive fashion. It was found that the T1 value was better than the transverse relaxation time constant (T2) for describing the evolution of the polymerization reactions, due to its greater sensitivity to paramagnetic effects. The TD‐NMR signal variation observed was linked to the formation, propagation and termination steps of the radical polymerization kinetics scheme. These first results may contribute to the application of real‐time monitoring of radical polymerization reactions employing low‐cost and robust TD‐NMR spectrometers. © 2018 Society of Chemical Industry

Superabsorbent hydrogels made from bio-sourced butyrolactone monomer in aqueous solution

A study of the radical polymerization kinetics of sodium 4-hydroxy-4-methyl-2-methylene butanoate with acrylamide in aqueous solution provides insights to the performance of superabsorbent hydrogels synthesized with equilibrium degree of swelling in the range of 6700–59 000%.

Microfluidic preparation of yolk/shell ZIF-8/alginate hybrid microcapsules from Pickering emulsion

We develop a facile method to fabricate yolk/shell and multi-yolk/shell ZIF-8/alginate hybrid microcapsules by first forming yolk/shell W/O ZIF-8 Pickering emulsions containing sodium alginate in water, followed by sodification of alginate to form the hybrid shell. Polymerization induced phase separation of a polyethylene glycol aqueous and acrylamide aqueous solution is used to form the yolk, and droplet coalescence is used to form multi-yolks. We examine the preparation conditions to obtain a stable ZIF-8 W/O Pickering emulsion. Further, these ZIF-8 Pickering emulsions can be converted to ZIF-8/alginate hybrid microcapsules with both hollow and yolk/shell structures by adding small amount of sodium alginate in the PEG solution, based on our finding that ZIF-8 can gelate sodium alginate. The ZIF-8/alginate hybrid microcapsules exhibit controlled release ability for Rhodamine B, with the yolk/shell one showing a lower dye release percentage. Furthermore, the release rate can be accelerated in an acid condition, resulting from the dissolution of ZIF-8.

Facile synthesis of gold nanoparticles in aqueous acrylamide solution

A method is advanced for preparing gold nanoparticles (NPs) at 50°C in aqueous acrylamide (AAm), which has the dual function of a reducing agent for HAuCl4 and a protective ligand for NPs. Nanoparticles have gold cores with the average size d Au = 20.9 ± 3.6 nm. The growth kinetics of NPs has been studied. Films of NPs have been produced on glass, silica, silicon, and polyethylene terephthalate (PET) substrates. The NPs and films have been characterized by UV-Vis and IR spectroscopy, X-ray powder diffraction, transmission and scanning electron microscopy, and atomic-force microscopy.

Modeling the Radical Batch Homopolymerization of Acrylamide in Aqueous Solution

A kinetic model for the radical homopolymerization of acrylamide in aqueous solution is developed, incorporating propagation and termination rate coefficients as functions of monomer concentration and including the formation and reaction of midchain radicals based on the insights and measured rate coefficients from recent pulsed‐laser studies. The model successfully represents the batch conversion profiles measured using an in situ NMR technique between 40 and 70 °C with initial monomer concentrations of 5 to 40 wt%, as well as the associated polymer molar mass distributions. In particular, the model captures the decreased rate that occurs at lowered monomer concentrations as a result of the formation of less‐active midchain radicals by backbiting. Previous literature data are also well represented by the model. image

Detection of acrylamide using a biodegradable zein-based sensor with surface enhanced Raman spectroscopy

In this study, a biodegradable zein/gold SERS platform was tested as a potential tool to detect acrylamide for the first time. It was found that the presence of acrylamide resulted in a characteristic marker SERS peak that did not exist in the background SERS spectrum of the sensor. This unique peak was at 1447 cm−1. This peak was used to detect and quantify acrylamide in aqueous solutions and a calibration curve was obtained using acrylamide solutions within the range of 10 mg/ml and 10 μg/ml. After 10 μg/ml of concentration, it was not possible to make reliable measurements. The error or variation for each concentration in the range of 0.4 mg/ml (for 1 mg/ml) – 1.8 mg/ml (for 10 mg/ml) was observed. SERS was found to be an accurate technique for quantification purposes, in the concentration range studied. The calibration curve had an R2 value of 0.93 and 0.97 (for log–log calibration curve). This was a proof-of-concept study to investigate the potential of a SERS sensor designed on a biodegradable platform and it was shown that this method can be potentially used with a careful design of acrylamide extraction from food samples.

Poly(acrylamide)-MWNTs hybrid hydrogel with extremely high mechanical strength

AbstractPoly(acrylamide)-multiwalled carbon nanotubes (PAAm-MWNTs) hybrid hydrogels were prepared through the radiation-induced polymerization and crosslinking of the aqueous solution of acrylamide and well-dispersed MWNTs for the first time. The PAAm gels obtained by the radiation-induced polymerization and cosslinking showed very high mechanical strengths, and the PAAm-MWNTs hybrid hydrogels had improved mechanical properties compared with the PAAm gels, and hence the PAAm-MWNTs hybrid hydrogels showed extremely high compressive and tensile strengths. The hybrid hydrogels with water contents more than 80 wt.% usually did not fracture even at compressive strengths close to or even more than 60 MPa and strains more than 97%. And the hybrid hydrogels had very high elongations (more than 2000% in some cases), especially when the water content was high. The tensile strengths were in sub-MPa. The hybrid PAAm-MWNTs hydrogel is one of the strongest hydrogel even made.

High molecular weight polyacrylamide nanoparticles prepared by inverse emulsion polymerization: reaction conditions-properties relationships

High molecular weight polyacrylamide (PAM) nanoparticle dispersions are products with wide application possibilities, the most important of which is in petroleum industry such as drilling fluid and flooding agent in enhanced oil recovery. For that aim, it is necessary to achieve complete control of the final dispersion and polymer properties during the synthesis step. In this work, PAMs were synthesized by inverse emulsion polymerization of aqueous acrylamide solution in cyclohexane in the presence of emulsifier mixture of Span 20 and Span 80. We present a comprehensive study of the effects of variation of all important reaction conditions (agitation rate, reaction time and temperature, initiator type and concentration, emulsifier HLB ratio and its concentration, and water to oil ratio) on final monomer conversion, reaction kinetics, polymer intrinsic viscosity and molecular weight, particle size and distribution, and colloidal stability. Finally, the relationships between the reaction conditions and the polymer properties were developed, which allowed determination of the ranges of variation of reaction conditions for optimal PAM properties for the oil industry applications: high molecular weight and intrinsic viscosity, nanosized polymer particles with narrow particle size distribution, and improved colloidal stability of the final dispersions.

In English

Photopolymerization of acrylamide in aqueous solutions induced by visible light (λ>400 nm) absorbed by colloidal particles of Cd x Zn 1–x S, Fe 2 O 3 and graphene oxide is reported. Depending on the photoinitiator nature, primary radicals are generated by monomer reduction with conduction band electrons (Cd x Zn 1–x S), monomer oxidation by the valence band holes (Fe 2 O 3 ) or by interaction between monomer and free radicals photoeliminated from graphene oxide. The photopolymerization rate increases proportionally to the conduction band potential of Cd x Zn 1-x S nanoparticles that depends on their composition. The Fe 2 O 3 -initiated acrylamide photopolymerization proceeds with comparable effectiveness in both deaerated and air-exposed aqueous solutions, the feature differing drastically from typical organic photoinitiators. On the basis of kinetic parameters the photopolymerization process was found to be of the chain free radical character with a principal chain termination route being macro-radicals recombination. The kinetic data also indicate a possibility of participation of the Cd x Zn 1–x S nanoparticles and graphene oxide in the chain termination.

Phase state of aqueous solutions of acrylamide–sodium acrylate copolymers in the presence of copper, zinc, and manganese ions

Introduction of copper(II), zinc(II), and manganese(II) ions into aqueous solutions of acrylamide–sodium acrylate copolymer leads to phase separation. The position of the boundary between the liquid phase and the precipitate is determined by the copolymer composition, its concentration in solution, and nature and concentration of the ion being introduced.

Uranyl Ion Uptake Properties of Highly Swollen AAm/SA/GEL/PVA Semi IPNs as Novel Biosorbent

ABSTRACTIn this study, uranyl ion adsorption from aqueous solutions has been investigated by highly swollen gelatin and poly(vinyl alcohol) based semi-interpenetrating polymer network systems of acrylamide/sodium acrylate. For this, chemically cross-linked copolymer of acrylamide/sodium acrylate hydrogels with gelatin and/or poly(vinyl alcohol) were prepared by free radical polymerization in an aqueous solution of acrylamide and sodium acrylate using ammonium persulfate/N,N,N′,N′-tetramethylethylenediamine as redox initiating pair in the presence of poly(ethylene glycol)diacrylate as a cross linker. Adsorption studies were investigated by spectrophotometric method at 25°C. Sorption capacity, removal efficiency, and partition coefficient of the hydrogels were investigated. Removal efficiency was changed within a range of 7.06–33.03%.

Mechanical properties and network structure of hydrophobic association hydrogels prepared from octylphenol polyoxyethylene(7) acrylate and sodium dodecyl sulfate

Hydrophobic association hydrogels(HA-gels) with high mechanical strength were prepared by free radical micellar copolymerization in aqueous solutions of acrylamide(AM), anion surfactant sodium dodecyl sulfate(SDS) and a small amount of hydrophobic monomer octylphenol polyoxyethylene(7) acrylate(OP-7-AC). We found that the molar ratio of SDS to OP-7-AC has a great effect on the tensile strength and other mechanical property parameters. The best ratio point R′ was determined. On the basis of Mooney theory and statistical theory, the critical tensile ratios and critical tensile strengths of the hydrogels were obtained, elastic parameters C 1 and C 2 were calculated via uniaxial tensile equation and structural parameters, such as the effective network chain density and the averaged molecular weight of the chain between cross-linking points of all the hydrogels were evaluated. The results indicate that the variation of mechanical property parameters depends on the number of effective cross-linking points and the match degree of long and short chains.