Acrylic Acid In Aqueous Solution Research Articles

PLP−SEC Study into Free-Radical Propagation Rate of Nonionized Acrylic Acid in Aqueous Solution

Pulsed laser polymerization (PLP) in conjunction with size-exclusion chromatography (SEC), both being carried out in the aqueous phase, was used to determine propagation rate coefficients, kp, of nonionized acrylic acid (AA) at temperatures between 2 and 25 °C and monomer concentrations, cAA, from 1 to 10 wt %. The product kpcAA,local is the primary experimental quantity deduced via the PLP−SEC technique. Assuming cAA,local to be identical to overall monomer concentration, cAA, yields apparent kp values, which, upon enhancing cAA, first increase and, after passing through a maximum at around 3 wt % AA, significantly decrease. A kp value as high as 180 000 L·mol-1·s-1 was determined for 3 wt % AA at 25 °C. The decrease observed toward higher AA concentration is fully consistent with what has been found in a preceding study into kp of nonionized AA at monomer concentrations of 20 and 40 wt %. At constant temperature, variations in apparent kp by about a factor of 3 are seen in the range up to 40 wt % AA. Di...

PbS nanocrystals embedded in microstructures produced by micromoulding in capillaries

The study presents a new method to prepare PbS nanocrystals embedded in poly(acrylic acid) (PAA) microstructures by micromoulding in capillaries (MIMIC). The micropatterns were fabricated first from aqueous solution of acrylic acid lead monomer, and subsequently solidified by γ-ray polymerization. The resulting samples were treated with aqueous Na 2S solution to convert Pb precursor to PbS in the matrix. The final micropatterns of PAA embedded with PbS nanocrystals were of high resolution. The products were characterized by IR, XRD, TEM and SPM, respectively, and the results demonstrated that PbS embedded in PAA was nanocrystals.

Aqueous solution polymerization of neutralized acrylic acid using Na 2 S 2 O 5 /(NH 4 ) 2 S 2 O 8 redox pair system under atmospheric conditions

Thickening is one of the main attributes of high molecular weight poly(sodium acrylate) as a water-soluble polymer. The acrylate polymer was prepared through polymerization of NaOH-neutralized acrylic acid in aqueous solution. The reaction mixture was open to the atmosphere, providing unrestricted access to oxygen. The sodium metabisulfite/ammonium persulfate redox system was used as an initiator in the free-radical polymerization. After prevailing on a few synthetic practical problems, certain parameters affecting the reaction and product characteristics were studied. The parameters were the initiator and monomer concentration, reaction temperature, pH, and chain transfer agent (i.e., isopropanol). As-synthesizedpolymers were purified and evaluated viscometrically by a Brookfield viscometer (0.5 Wt% polymer solution in distilled water at 25°C). Intrinsic viscosity, [ m ], was also measured to calculate the viscosity average molecular weight (M v ) based on the corresponding Mark-Hawink-Sakurada equation. Changes of the isolated polymer yield, viscosity, M v , and a couple of indirect kinetic factors including gelation/reaction times and temperature were investigated according to the mechanism and known kinetic relationships of the free-radical addition polymerization. Finally, a useful Brookfield viscosity-M v curve was obtained and suggested to use for facile estimation of the average molecular weight of a typical poly(sodium acrylate) sample having medium to high molecular weight.

Immobilization of Viologen Moieties on Poly(Acrylic Acid)-Grafted Polyethylene Surface

Immobilization of viologen moieties on low-density polyethylene(PE) film was carried out by a surface graft polymerization technique in this study. Graft polymerization of acrylic acid was performed onto the surface of PE film pre-treated with Ar plasma. Following the plasma treatment and the subsequent exposure to air to introduce peroxides onto PE film surface, graft polymerization was allowed to proceed from the polymer peroxides in deaerated acrylic acid aqueous solution. Carboxyl groups of the PAAc-grafted PE film were reacted with epoxy groups of epibromohydrin, to introduce bromoalkyl groups to the surface of PE film. Viologen moieties were introduced onto the surface of PE film by the Menschtkin reaction between bromoalkyl groups and 4,4’-bipyridine, followed by the reaction with n-propyl bromide. The PE film containing viologen moieties exhibited the photochromism. Attenuated total reflection Fourier-transform infrared spectroscopy(ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and UV-visible studies were conducted for characterizing the surfaces of these films during the various stages of the reaction.

Platelet adhesion on laser‐induced acrylic acid–grafted polyethylene terephthalate

AbstractTo improve blood compatibility, acrylic acid (AAc) was grafted onto a polyethylene terephtalate (PET) film surface using lasers. The PET surface was irradiated with a CO2 pulsed laser, and then graft copolymerization was carried out in an aqueous solution of AAc in the presence of Mohr's salt. Different techniques such as attenuated total reflectance Fourier transform infrared spectroscopy (ATR‐FTIR), scanning electron microscopy (SEM), and contact angle measurements were used to characterize the modified PET surface. The ATR‐FTIR spectra confirmed the creation of new functional groups on the PET surface, and contact angle measurements revealed that the hydrophilicity of the PET surface increased as a result of the AAc graft polymerization. The electron micrographs showed that the grafting changed the surface morphology of the PET film. To evaluate the blood compatibility in vitro, the number of platelets adhering to the modified PET surface was determined using lactate dehydrogenase (LDH) activity measurement. The data from LDH method indicated that the extent of platelet adherence on the unmodified PET was much higher than that on the AAc grafted PET. The morphology of adhered platelets on the PET surface was investigated by SEM. The results showed that platelet adhesion and activation onto the PET surface was reduced because of AAc graft polymerization. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3191–3196, 2002

Gas-Chromatographic Determination of Acrylic Acid in Aqueous Solutions

A procedure was developed for determining acrylic acid in aqueous solutions at its concentration within 0.5-20 MPC.

Toughness enhancement of poly(ethylene terephthalate) with functionalized ultrahigh molecular weight polyethylene

AbstractUltrahigh molecular weight polyethylene (UHMWPE) is available commercially in the form of powder, consisting of fine primary particles, 1–5 μm in diameter, agglomerated into secondary “free‐flowing” particles with overall dimensions in the region of 50 to 150 μm. These are normally sufficiently coherent and retain their conglomerated particulate structure when blended with other polymers because of the extremely high viscosity of UHMWPE. In this study the surface of the agglomerated primary particles was acid functionalized by reactions with aqueous solutions of acrylic acid, after being irradiated with γ‐radiation at 15–45 kGy. The acid groups were used to introduce a glycidoxyl functionality through reactions with a difunctional cycloaliphatic epoxy resin and also to a “partial” metal carboxylate functionality through reactions with zinc acetyl acetonate. When blended with polyethylene terephthalate (PET) in either a small‐batch mixer or in a twin‐screw extruder all the treated powders, except those functionalized with acrylic acid, were broken down to their primary size and were uniformly dispersed and strongly bonded to the surrounding matrix. The blends containing the deglomerated particles were found to have much greater ductility and toughness than those produced from both untreated and acid functionalized powder. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2972–2986, 2001

Aqueous Phase Size-Exclusion-Chromatography Used for PLP−SEC Studies into Free-Radical Propagation Rate of Acrylic Acid in Aqueous Solution

Pulsed laser polymerization (PLP) in conjunction with analysis of the resulting polymer by size-exclusion-chromatography (SEC) was used to measure propagation rate coefficients, kp, of acrylic acid (AA) in aqueous solution at concentrations of 20 and 40 wt % and temperatures between 2.6 and 28.5 °C. Under these conditions, more than 99% of acrylic acid exists in the nonionized form. The molecular weight distribution (MWD) of poly(AA) is directly measured by aqueous SEC. The kp values at 20 wt % are about 60% higher than at 40 wt %. The activation energy of kp is close to 12.0 kJ·mol-1 at both concentrations. At 25 °C and 20 wt %, kp of AA in aqueous solution exceeds 100 000 L·mol-1·s-1 which is the highest kp value determined by the PLP−SEC technique so far.

Development of acrylamide polymers for the treatment of waste water

Water-soluble acrylamide polymers were prepared by different polymerization techniques such as the use of free radical initiators, electrochemical initiation, ultrasonic waves, photochemical sensitizers, ultraviolet radiation, radiation, electron beam radiation, and an aqueous redox system. The physical and chemical properties of polyacrylamide are discussed. Acrylamide polymeric resins were prepared by γ-irradiation-initiated template polymerization of acrylic acid on acrylamide polymers. The grafting of acrylic acid on polyacrylamide produces poly(acrylamide-acrylic acid) resin. The capacity of the resins was studied under different experimental conditions by varying the radiation dose, the monomer concentration, the polymer/monomer molar ratio, and the composition of the added polymer. Acrylamide polymeric gels were prepared by copolymerization of acrylamide with acrylic acid in aqueous solution and template polymerization of dimethylaminoethyl methacrylate on poly(acrylamide-acrylic acid). Acrylamide polymeric materials were used in the treatment of waste water for the removal of metallic ions from their corresponding metal salt solution. They were also used for the separation of radioactive isotopes from radioactive liquid waste. The mechanism of interaction of acrylamide polymeric materials with metallic ions in aqueous solutions is discussed.

Surface structure of low density polyethylene films grafted with acrylic acid using corona discharge

Chemical composition, morphology, and crystalline structure of low density polyethylene (LDPE) films surface grafted with acrylic acid (AA) using corona discharge were studied by attenuated total reflection infrared (ATR-IR), electron spectroscopy for chemical analysis (ESCA), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and wide angle X-ray diffraction (WAXD) techniques. The grafted film surface is covered with grafted chains. After grafting for 3.0 h in 20% aqueous solution of AA, the depth of the grafted layer is more than 10 nm. A grain structure was observed on the grafted surfaces which was probably caused by the isolated dispersion of active sites generated by corona discharge, and these active sites initiated the graft copolymerization. However, surfaces of grafted films were smoother than that of ungrafted ones. DSC curves of grafted films show a small peak at about 100°C due to vaporization of adsorbed water. The longer the graft copolymerization time, i.e. the higher the graft degree of AA on LDPE, the higher the amount of adsorbed water. The position of each peak in WAXD patterns, crystal axial length, crystal plane distance and crystal grain size remain almost unchanged during the graft copolymerization time of 2.0 h. However, when the graft copolymerization time reaches 3.0 h, twin peaks at about 21.4° and 22.0° are observed, indicating that a different crystal form is formed at longer copolymerization time, i.e. at a higher graft degree.

Graft copolymerization of PU membranes with acrylic acid and crotonic acid using benzoyl peroxide initiator

To improve water wettability of polyurethane (PU), graft copolymerization with acrylic acid (AA) and crotonic acid (CA) was performed using a benzoyl peroxide (BO) initiator. The grafting reaction was carried out by placing the membranes in aqueous solutions of AA and CA at constant temperatures. Variations of graft yield with time, temperature, initiator, and monomer concentrations were investigated. The optimum temperature, polymerization time, monomer, and initiator concentrations for AA were found to be 70°C; 3 h; 1.5 M; 5.0 × 10−2M, and for CA 70°C; 1 h; 1.5 M; 4.0 × 10−2M, respectively. The grafting membranes were characterized by FTIR spectroscopy and scanning electron microscopy (SEM) analysis, and the effect of grafting on equilibrium water content (EWC) of PU membranes was obtained by swelling measurements. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2690–2695, 2001

Study of water sorption in rubbers by acoustic microscopy

Acoustic microscopy has been used to examine changes during water swelling at the surface of a rubber previously treated with an acrylic monomer. Surface modification was carried out with acrylic acid either in aqueous solution or in the vapour phase, and a photografting reaction was achieved with an aqueous solution of acrylic acid in the presence of a photo-initiator. Water sorption induces modifications of the mechanical properties, transforming a rigid polymer into a soft material. Therefore, the acoustic impedance of the material decreases during the swelling process and the evolution of acoustic reflection coefficient is followed. The potential of ultrasonic measurements as an in situ and non-destructive dynamic analysis technique is demonstrated. Mapping of grafted and ungrafted areas on a rubber surface is obtained with acoustic microscopy. © 2000 Society of Chemical Industry

Metal salts interaction with acrylic acid-maleic acid copolymer: An infrared spectroscopic study

A study was carried out in which aqueous solutions of acrylic acid–maleic acid copolymer (mole ratio of monomers: 3:2) were diluted with solutions of various salts [NaCl, MgCl2, CaCl2, SrCl2, ZnCl2, Al(NO3)3 and Fe(NO3)3]. This copolymer was found to interact with all these salts to make solutions of enhanced acidity that infrared spectroscopy suggested was a result of charge stabilization of the polyanion by counterions occupying atmospheric or site-bound locations. The cations of the salts NaCl, MgCl2, CaCl2 and SrCl2 appeared to occupy atmospheric positions only; in contrast, with poly(acrylic acid) they showed some site binding. Zinc ions, on the other hand, gave identical bridging bidentate interactions with both polymers. The cations from the trivalent salts Al(NO3)3 and Fe(NO3)3 were atmospheric and site bound (bridging bidentate), respectively, and these were also different from their interactions with poly(acrylic acid). The addition of Fe(NO3)3 to the copolymer caused gelation, as with poly(acrylic acid), but formation of the gel was slower and did not result in phase separation. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 78: 1680–1684, 2000

Free Radical Polymerization in Aqueous Solution of Acrylic Acid Mediated by Nitroxides Originated from NaNO2

ABSTRACT A series of investigations was carried out focusing on the confinement of the Trommsdorf (gel) effect in radical polymerization of acrylic acid, AA, in its Na-form. Sodium nitrite, NaNO2, functioning at room temperature as an inhibitor for water-soluble monomers, proved to be an effective mediator in polymerizations carried out at t = 90 °C. As a result it was possible to polymerize AA at a high initial monomer concentration, i.e. [M]0 = 40 g/dl. Therefore, concentrated solutions of NaPAA in water were obtainable in a one-step process. It was found that NaNO 2 retards the onset of polymerization up to 60 °C at which temperature only a small degree of conversion α= 30% was reached after 40 hours. On the other hand, without added NaNO2 a less concentrated monomer solution, having [M]0 = 10 g/dl was polymerized to α= 96% at 60 °C after 40 minutes. At 90°C, the polymerization of NaAA no longer appeared to be retarded by sodium nitrite, since in 40 g/dl solutions high degrees of conversion were obtainable within reasonable time periods, without any sign of autoacceleration. As NaNO2 generates nitroxides, it seemed reasonable to analyze the progress of the mediated polymerizations as an approach to “livingness”. In fact, some increase inover time of polymerization, τ, was observed, but generally the criteria for a “living polymerization” remained unfulfilled. Relatively high coefficients of polydispersityranging between 6.50 and 9.62 were found for all the NaNO2 mediated poly(acrylic acid)s. A value of the same order resulted for the non-mediated poly(acrylic acid).

Preparation and characterization of a homobifunctional silicone rubber membrane grafted with acrylic acid via plasma-induced graft copolymerization

Polyacrylic acid (PAA) was grafted onto the surface of silicone rubber membrane (SR) by plasma-induced graft copolymerization (PIP). Ar-plasma was used to activate the surface of SR. Also, a determination was made of the influences of plasma treatment power, pressure, time, grafted copolymerization reaction time, and monomer concentration on polymerization yield. The surface properties of SR were measured by ATR-FTIR, ESCA, and SIMS. In those analyses, the elemental composition and different carbon bindings on the surface of SR were examined by ESCA with the amount of O1s/C1s being approximately 0.7 at 60 s by Ar-plasma treatment (60 W, 200 mtorr). The peroxide group introduced on SR was measured via 1,1-diphenyl-2-picryhydrazyl (DPPH). The optimum amount of peroxide groups was 6.85 × 10−8 mol/cm2 at 60 s of Ar-plasma treatment. The peroxide group (33D peak) was introduced onto the surface of SR by negative spectra of SIMS analysis after SR treatment by Ar-plasma. An increase was obtained in grafted polymerization yield with a region of 5 to 50% (v/v) of acrylic acid aqueous solution. Both sites of polyacrylic acid were detected after staining by toluidine blue O. That is, a homobifunctional membrane was developed via this surface modification method. © 1996 John Wiley & Sons, Inc.

Sorption and pervaporation of benzene-cyclohexane mixtures through composite membranes prepared via concentrated emulsion polymerization

Composite membranes have been prepared starting from concentrated emulsions of styrene in aqueous solutions of acrylic acid as precursors. Each of the phases of the emulsion contained a suitable initiator and the continuous phase contained a dispersant (sodium dodecylsulfate). The polymerization of the precursor generated a composite consisting of particles of dispersed phase imbedded in the continuous phase. To obtain the membranes, the polymer powders generated via grinding were subjected to hot pressing. The mechanical properties of the membranes have been improved by dissolving either butyl acrylate or styrene-butadiene-styrene three block copolymer in styrene. The membranes have been used to separate benzene from benzene-cyclohexane mixtures. The components of the membranes have been selected because polystyrene swells well in benzene and much less in cyclohexane, while the poly (acrylic acid) does not swell well in either of the components and can, therefore, maintain the integrity of the membrane. The mechanical and sorption behaviors of the membranes as well as their pervaporation capabilities were investigated.

Immobilization of poly(ethylene oxide) on polyethylene using a plasma‐induced graft copolymerization process

AbstractA radio‐frequency glow discharge induced graft copolymerization process has prepared a PAAc‐grafted PE film in this present study. Poly(ethylene oxide) (PEO) was then covalently immobilized onto PAAc‐grafted PE film by a chemical coupling reaction. Carboxylic groups were introduced onto the surface of PE film by exposing the film to an Ar plasma, and the plasma‐treated film was then next reacted with a 50% acrylic acid aqueous solution. These functional groups were reacted with bisamino PEO by a coupling agent CMC. ESCA, IR, and water contact angle studies were conducted for characterizing the surfaces of these films during the varied stages of the reaction. Increasing the molecular weight of the PEO attached to the PAAc‐grafted PE resulted in an increased wettability of the films. © 1993 John Wiley & Sons, Inc.

Radiation‐grafting of acrylic acid onto ultrahigh molecular, high‐strength polyethylene fibers

AbstractRadiation‐induced grafting of acrylic acid onto ultrahigh molecular weight (UHMW) high‐strength polyethylene fibers to impart heat resistance and dyeability was undertaken. A preirradiation method was employed for grafting in an aqueous solution of acrylic acid containing a small amount of Mohr's salt as inhibitor. The grafting rate for UHMW high‐strength polyethylene fibers is one‐tenth of that for high‐density polyethylene fibers currently in use, and one‐hundredth, for high‐density polyethylene film. It has become clear that the preirradiation dose should be as low as 1 Mrad to keep the high strength of the starting fibers. The starting UHMW high‐strength polyethylene fiber begins to shrink remarkably at around 145°C, showing a maximum shrinkage of 90%, and then breaks at 154°C. When a 24% acrylic acid graft is converted to calcium salt, the grafted fiber retains the fiber form even at 300°C and gives only a maximum shrinkage of 11%. The less than 1% acrylic acid graft UHMW high‐strength polyethylene fibers and their calcium salt can be dyed to a deep shade with cationic dyes, whereas the starting fibers cannot be dyed with usual dyes including the cationic dye. © 1993 John Wiley & Sons, Inc.

Synthesis of porous polymeric membranes by polymerization of micro-emulsions

In this study the polymerization of monomer-containing micro-emulsions to yield porous polymeric membranes is demonstrated. A micro-emulsion system composed of methyl methacrylate and acrylic acid as monomers, ethyleneglycol dimethacrylate as crosslinking agent, sodium dodecylsulfate as surfactant and water was studied. An identical surfactant-free system, formed using the same monomers, crosslinking agent and water but without surfactant, was also studied and the micro-emulsions formed at certain compositions were polymerized. Our earlier work with these systems had indicated the porous morphology of the polymer to be dependent on the microstructure of the precursor micro-emulsion. In the present study micro-emulsion compositions which showed inferential evidence of a bicontinuous structure were polymerized to form membranes by using photo-initiated polymerization with ultra-violet radiation. The membranes formed had a thickness of 10–12 μm. The swelling characteristics in water of the polymeric material constituting the membranes was evaluated as a function of pH. The tensile properties of the membranes were also evaluated. The permeability of the membranes was examined using aqueous solutions of acrylic acid. The results indicate the permeability of the membranes to be dependent on the composition of the precursor micro-emulsion due to the relationship between the polymer morphology and micro-emulsion structure. This study conclusively shows the feasibility of synthesizing porous polymeric membranes by utilizing the structure of micro-emulsions.

Glow‐discharge‐induced graft polymerization of acrylic acid onto poly[1‐(trimethylsilyl)‐1‐propyne] film

AbstractGraft polymerization of acrylic acid onto poly[1‐(trimethylsilyl)‐1‐propyne] [poly(TMSP)] film was examined. The water contact angle of poly(TMSP) film decreased remarkably from 90 to 15° by plasma treatment, which gradually increased up to 40° after several days. When the film exposed to a glow discharge was heated in an aqueous solution of acrylic acid at 80°C for 24 h, graft polymerization proceeded on the film surface, which was confirmed by ATR‐IR and ESCA spectra. Graft polymerization effectively occurred above a threshold temperature (80°C). The water contact angle of the grafted film was about 30°, and did not change with time. In contrast, when a poly(TMSP) film exposed to UV irradiation was heated in an aqueous solution of acrylic acid, graft polymerization took place not only on the film surface but also inside the film.