Effect Of Comonomer Composition Research Articles

Gamma radiation-induced preparation of poly(1-vinyl-2-pyrrolidone-co-sodium acrylate) for effective removal of Co(II), Ni(II), and Cu(II)

Clearing the water and wastewater from toxic heavy metals has received attentions from many researchers and scientists. In this study, poly(1-vinyl-2-pyrrolidone-co-sodium acrylate), P(VP-SA), was prepared by gamma radiation-induced copolymerization of VP and SA and utilized for the effective removal of cobalt(II), nickel(II), and copper(II) from their aqueous solutions. Effect of comonomer composition and concentration besides the adsorbed dose on the conversion percentage and the reduced viscosity was studied. The formed copolymer was characterized using Fourier transform infrared and gel permeation chromatography analysis, and the thermal stability was examined using thermogravimetric analysis. The influence of the adsorption conditions such as contact time, pH, copolymer concentration, and initial metal ion concentration on the metal ion binding capacity was tested. Pseudo-first-order, pseudo-second-order, and intraparticle diffusion adsorption models were used to explain the adsorption kinetics. Finally, the equilibrium adsorption data fitted well with Langmuir isotherm model, and the maximum adsorption amounts on P(VP-SA) copolymer calculated by Langmuir equation were 425.60, 93.01 and 450.81 mg g−1 for Cu+2, Ni+2, and Co+2, respectively.

Guar Gum-Grafted Terpolymer Hydrogels for Ligand-Selective Individual and Synergistic Adsorption: Effect of Comonomer Composition.

Grafting of guar gum (GG) and in situ strategic attachment of acrylamidosodiumpropanoate (ASP) via solution polymerization of acrylamide (AM) and sodium acrylate (SA) resulted in the synthesis of a sustainable GG-g-(AM-co-SA-co-ASP)/GGAMSAASP interpenetrating polymer network (IPN)-based smart superadsorbent with excellent physicochemical properties and reusability, through systematic optimization by response surface methodology (RSM) for removal of methyl violet (MV) and/or Hg(II). The relative effects of SA/AM ratios, in situ allocation of ASP, grafting of GG into the AMSAASP terpolymer, ligand-selective superadsorption mechanism, and relative microstructural changes in individually/synergistically-adsorbed MV–/Hg(II)–/Hg(II)–MV–GGAMSAASPs were determined by extensive analyses using Fourier transform infrared (FTIR), proton nuclear magnetic resonance, ultraviolet–visible (UV–vis), and O 1s-/N 1s-/C 1s-/Hg 4f7/2,5/2-X-ray photoelectron spectroscopies, thermogravimetric analysis, differential scanning calorimetry, X-ray diffraction, field emission scanning electron microscopy, and energy-dispersive spectroscopy and were supported by % gel content, pHPZC, and % graft ratio. The ionic/covalent-bonding, monodentate, bidentate bridging, and bidentate chelating coordination between GGAMSAASPs and Hg(II), and MV+–Hg(II) bonding were rationalized by FTIR, UV–vis, fitment of kinetics data to the pseudo-second-order model, and thermodynamic parameters. The maximum adsorption capacities of 49.12 and 53.28 mg g–1 were determined for Hg(II) and MV, respectively, under optimized conditions.

Swelling behavior of poly (N-hydroxymethylacrylamide-co-acrylic acid) hydrogels and release of potassium nitrate as fertilizer

Abstract Poly (N-hydroxymethylacrylamide-co-acrylic acid) [P(NHMA-AAx)] hydrogels were prepared by free-radical polymerization in aqueous solution at 56°C, using N,N′-methylenebisacrylamide as the cross-linking agent. The synthesized hydrogels were subsequently investigated by a series of characterization techniques including Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis and differential scanning calorimetry analysis. The effects of comonomer composition in the feed, pH, temperature and ionic strength on the swelling behavior were studied. Results indicated that the swelling capabilities of P(NHMA-AAx) hydrogels decreased with the increase in N-hydroxymethylacrylamide (NHMA) content in the polymeric matrix and ionic strength of the medium. Additionally, the hydrogels showed both temperature and pH responses. The dynamic swelling behaviors of hydrogels at different pH values followed a non-Fickian type. The P(NHMA-AAx) hydrogels were also loaded with potassium nitrate (KNO3) as a model agrochemical, and the release kinetics of fertilizer from the hydrogels was studied as a function of KNO3 and NHMA concentrations. Moreover, various kinetic parameters, such as release exponents and diffusion coefficients, were calculated.

Further Insight into the Mechanism of Poly(styrene-co-methyl methacrylate) Microsphere Formation.

Polymeric microspheres have been utilized in a broad range of applications ranging from chromatographic separation techniques to analysis of air flow over aerodynamic surfaces. The preparation of microspheres from many different polymer families has consequently been extensively studied using a variety of synthetic approaches. Although there are a variety of methods of synthesis for polymeric microspheres, free-radical initiated emulsion polymerization is one of the most common techniques. In this work, poly(styrene-co-methyl methacrylate) microspheres were synthesized via surfactant-free emulsion polymerization. The effect of co-monomer composition and addition time on particle size distribution, particle formation, and particle morphology were investigated. Particles were characterized using dynamic light scattering (DLS) and scanning electron microscopy (SEM) to gain further insight into particle size and size distributions. Reaction kinetics were analyzed alongside of characterization results. A particle formation mechanism for poly(styrene-co-methyl methacrylate) microspheres was proposed based on characterization results and known reaction kinetics.

Study of Swelling Properties and Thermal Behavior of Poly(N,N-Dimethylacrylamide-co-Maleic Acid) Based Hydrogels

Hydrogels copolymers N,N-dimethylacrylamide (DMA) and maleic acid (MA) were prepared by free-radical polymerization at 56°C in aqueous solution, using N,N-methylenebisacrylamide (NMBA) as cross-linking agent and potassium persulfate (KPS) as initiator. The effects of comonomer composition, cross-linker content, and variation of pH solutions on the swelling behavior of polymers were investigated. The obtained results showed an increase of the swelling of poly(N,N-dimethylacrylamide-co-maleic acid) (P(DMA-MAx)) as the content of maleic acid increases in the polymeric matrix, while they indicate a great reduction of the degree of swelling as the cross-linking agent ratio increases. It was also shown that the swelling of copolymer hydrogels increased with the increase of pH and the maximum extent was reached at pH 8.7 in all compositions. Fourier transform infrared spectroscopy (FTIR) revealed the existence of hydrogen bonding interactions between the carboxylic groups of MA and the carbonyl groups of DMA. Differential scanning calorimetry analysis (DSC) showed an increase of the glass-transition temperature (Tg) as concentrations of MA and NMBA increased. Thermogravimetric analysis (TGA) of copolymers was performed to investigate the degradation mechanism.

Synthesis and expansion characteristics of expandable styrene/methyl methacrylate copolymer beads: The effects of monomer composition and cell structure modifying aid

Parts cast of metals such as iron, using expandable polystyrene foams, may have an unacceptable amount of surface defects, such as lustrous carbon. The use of foams made of styrene/methyl methacrylate copolymers can improve the quality of foam molds and metal parts made using such molds. In this work, expandable copolymers were synthesized by suspension copolymerization of styrene and methyl methacrylate in the presence of blowing agents (pentane isomers). When the surrounding temperature was high enough to vaporize the blowing agent and soften the polymer shell, the beads were expanded. The effects of monomer composition and cell structure modifying aid (polyethylene wax) on the particle size, average molecular weight and molecular weight distribution of synthesized copolymer, pentane content and expansion properties (density, residual pentane of pre-expanded particles and cell structure) were investigated. The results showed that monomer composition had a significant effect on the copolymerization kinetic and the copolymer molecular weight. In addition, cell structure, cell size and cell size distribution of the pre-expanded particles were strongly influenced by cell structure modifying aid concentration. The effects of comonomer composition and copolymer particle size on pentane content of expandable particles were also studied.

Crystallization kinetics and morphology of biodegradable poly(butylene succinate-co-ethylene succinate) copolyesters: effects of comonomer composition and crystallization temperature

The crystallization kinetics and morphology of a series of biodegradable poly(butylene succinate-co-ethylene succinate) (P(BS-co-ES)) with ethylene succinate (ES) comonomer composition ranging from 13 to 28 mol% were investigated with various techniques and compared with those of the homopolymer poly(butylene succinate) (PBS) in this work. The crystal structures of P(BS-co-ES) are the same as that of neat PBS, but the crystallinity decreases slightly with increasing the ES composition. The glass transition temperature increases slightly while the nonisothermal melt crystallization peak temperature and melting point decrease for P(BS-co-ES) with increasing the ES composition; moreover, the equilibrium melting point temperature of P(BS-co-ES) is also reduced. The overall isothermal crystallization kinetics of P(BS-co-ES) was studied and compared with that of neat PBS. The crystallization mechanism does not change for either neat PBS and P(BS-co-ES) while the overall crystallization rates of P(BS-co-ES) decrease with increasing ES composition and crystallization temperature. The spherulite growth rates of P(BS-co-ES) also decrease with increasing ES composition and crystallization temperature. Both neat PBS and P(BS-co-ES) exhibit a crystallization regime II to III transition independent of ES composition; moreover, the crystallization regime transition temperature shifts to lower temperatures with increasing the ES composition.

Antistatic coating material consisting of poly (butylacrylate-co-styrene) core-nickel shell particle

A transparent and antistatic coating material consisting of polymer core-metal shell particle was prepared. As a polymer core, poly(butylacrylate-co-styrene)s ([P(BA-co-sty)s]) with various compositions of butylacrylate and styrene were synthesized by emulsion polymerization. And the effect of comonomer composition on the thermal property of polymer core particle was investigated. By electroless plating method, the nickel particles were formed and deposited on the surface of P(BA-co-Sty) particles to form P(BA-co-Sty) core-nickel shell composite particles. SEM observation confirms that the nickel particles with size of 15 nm are distributed on the surface of the polymer core particles. The surface resistance of P(BA-co-Sty) core-nickel shell composite is 0.8×10 8 Ω/cm 2, enough to act as antistatic coating material.

Synthesis and swelling behavior of poly(2‐dimethylaminoethyl methacrylate‐co‐N‐hydroxymethyl acrylamide) hydrogels

AbstractCrosslinked poly(2‐(N,N‐dimethylamino)ethyl methacrylate‐co‐N‐hydroxymethyl acrylamide) poly(DMAEMA‐co‐NHMAAM) copolymers were synthesized using ammonium persulfate (APS)/N,N,N′,N′‐tetramethyl ethylenediamine (TEMED) as initiator/accelerator system in the presence of tetraethyleneglycol diacrylate (TEGDA) as crosslinker in water at 60°C. The effects of comonomer composition in the feed, pH of the swelling medium, and the temperature on the equilibrium swelling (ES) values of hydrogels were investigated. While the initial total monomer concentration was kept constant at 0.5 or 1 mol/l, the contents of APS and TEGDA in the feed were 1 mol% of the total monomers. ES values of DMAEMA‐NHMAAM gels increased with the increase in DMAEMA content in the feed. Although DMAEMA‐NHMAAM hydrogels containing up to 30 mol% were transparent in appearance, the presence of 40% DMAEMA in the copolymer worsened its transparency. ES values of the copolymer gels with high DMAEMA contents increased with both temperature and the pH of swelling medium. Copyright © 2006 John Wiley & Sons, Ltd.

Probing the Surface of Polymer Colloids by Conductometric Surfactant Titration

This work revisits the use of surfactant titrations for the characterization of latex particle surfaces. Experiments were performed to study the effect of comonomer composition and the effect of acid comonomers, and the technique is applied to the characterization of particle morphology in composite latices for several different systems. It is confirmed that the packing density of surfactant on a polymer surface is a linear function of copolymer composition. Inclusion of acid comonomers has the expected effect of decreasing the amount of surfactant adsorbed on the polymer surfaces. The usefulness of the technique in the determination of particle morphology is demonstrated, in particular toward the detection of thin layers of either seed or second-stage polymer on the particle surface which are not easily detected by other techniques such as transmission electron microscopy (TEM). Finally, it is shown that the use of acid comonomers in composite particles greatly reduces the usefulness of the surfactant titration technique for morphology characterization. A possible explanation for this effect is proposed.

Combinatorial investigation of the structure-properties characterization of photopolymerized dimethacrylate networks

The effects of co-monomer composition and irradiation time in a model two-component dimethacrylate dental resin blend were evaluated using combinatorial methods to determine the degree of methacrylate conversion and resulting mechanical properties. 2-Dimensional gradient samples varying in monomer composition and light exposure time were fabricated. The conversion was measured using near infrared spectroscopy (NIR) and the mechanical properties (i.e., hardness and elastic modulus) were determined using nanoindentation via the continuous stiffness method. An excellent correlation was observed between the reaction conversion and mechanical properties for the cross-linked networks. The methacrylate conversion ranged from 40% to 85% and the mechanical properties increased over two orders of magnitude over this conversion range. The ultimate reaction conversion and mechanical properties depended on both the co-monomer composition and cure time.

Cloth filter for recovery of uranium from radioactive waste

A cloth filter incorporated with amidoxime/carboxyl groups was synthesized for recovery of uranium from radioactive waste obtained from nuclear fuel fabrication laboratories. The cloth filter was synthesized by radiation-induced grafting of acrylonitrile/methacrylic acid (AN/MA) onto a cotton cloth and followed by amidoximation reaction at a weight ratio of AN to MA of 80/20. The effect of comonomer composition on the grafting ratio and AN composition in the graft chain was studied. The reactivity of AN for grafting into the cotton cloth was found to be less than that of the MA acid. The incorporation of the functional groups was confirmed by FT–IR spectra. The cloth filter possessed good mechanical properties and thermal and chemical stability suitable for practical use. The uranium uptake ratio reached 95% at 298K and pH 9–9.5.

Radiation grafting from binary monomer mixtures. I. Vinyl ether of monoethanolamine and vinyl ether of ethyleneglycol

Gamma-radiation grafting of vinyl ether of monoethanolamine and vinyl ether of ethyleneglycol (VEEG) on polyethylene films has been studied from binary monomer mixtures. The effect of co-monomer composition and total exposure radiation dose on the grafting process is investigated. A combination of potentiometric and gravimetric techniques is applied to determine the grafting degree of each monomer in the final graft copolymer. The presence of more active monomer VEEG in the mixture was found to enhance the grafting of both monomers because the increasing of copolymerization rate which in turn increases the total grafting degree. The modification of the hydrophilic properties of the graft copolymer is studied by examining the grafted films for water- and copper (II) ions uptake.

Effect of comonomer composition on the controlled free-radical copolymerization of styrene and maleic anhydride by reversible addition–fragmentation chain transfer (RAFT)

Controlled free-radical copolymerization of styrene and maleic anhydride was performed in 1,4-dioxane or tetrahydrofurane solution at 60 °C using the RAFT technique. The effect of monomer feed ratio on copolymerization kinetics and on control over molar mass distribution was examined. It was shown that polymerization was faster and quality of control was poorer when the proportion of maleic anhydride in the monomer feed was larger. These features were assigned to a decrease in the chain transfer constant of the polymeric RAFT agent, most probably due to an increase in the apparent rate constant of propagation with the proportion of maleic anhydride.

Formation of Mesoglobular Phase of Amphiphilic Copolymer Chains in Dilute Solution: Effect of Comonomer Composition

Poly(N-isopropylacrylamide) (PNIPAM) is a thermally sensitive polymer with a lower critical solution temperature (∼32 °C) in water. Its copolymerization with hydrophilic vinylpyrrolidone (VP) at temperatures higher and lower than its LCST respectively resulted in segmented and random VP distributions. As the solution temperature increases, PNIPAM changes from hydrophilic to hydrophobic at ∼32 °C so that copolymer P(NIPAM-co-VP) becomes amphiphilic in water at higher temperatures. The association of two pairs of such copolymers with a similar chain composition and length, but different comonomer distributions, in water at temperatures higher than 32 °C was studied by laser light scattering. A limited number of neutral P(NIPAM-co-VP) chains can associate to form narrowly distributed stable mesoglobules existing between single-chain collapsed globules and macroscopic precipitates. The copolymer chains with a segmented VP distribution aggregate more readily to form larger mesoglobules than their counterpart w...

Copolymerization of Benzidine with Substituted Anilines: A Comparative Study

Copolymers of benzidine and aniline derivatives were prepared chemically and electrochemically. A study of the effect of comonomer composition on the thermal and electrical properties of copolymers was carried out. Copolymers were found to have more electrical conductivity compared to polybenzidine. With increase in temperature, the copolymers show semiconducting behavior similar to polybenzidine. Homopolymers, as well as copolymers, show good thermal stability.

FREE RADICAL COPOLYMERIZATION AND KINETIC TREATMENT OF CYCLOHEXENE WITH N-PHENYLMALEIMIDE

The copolymerization of cyclohexene (M1) and N-phenylmaleimide (M2) in chloroform with 2,2'-azo-bis(isobutyronitrile) as an initiator was investigated. The copolymerization of N-phenylmaleimide with cyclohexene in chloroform proceeded in a homogeneous system to give an alternating copolymer over a wide range of the comonomer composition in the feed. The kinetic parameters, such as reactivity ratio, overall activity energy and the effect of comonomer composition on the initial copolymerization rate (Rp) were determined. The bimolecular termination of the copolymerization was proved. A kinetic treatment based on the model of mechanism was proposed and used to test the copolymerization of cyclohexene and N-phenylmaleimide and to quantitatively estimate the k21/k12 value.

The effect of comonomer composition, silane heating, and filler type on aqueous TEGDMA leachability in model resin composites.

Experimental composites using either bisGMA/TEGDMA or UEDMA/ TEGDMA matrices, quartz or barium glass fillers, and 2 different filler silanization methods were evaluated regarding monomer leachability in distilled water. The leached amount was detected and quantified using gas chromatography. The results showed that twice as much TEGDMA is leached from a bisGMA/TEGDMA based composite than from an UEDMA/ TEGDMA based composite, when both contain 50 wt% TEGDMA. The hypothesis suggested that the higher degree of cure of UEDMA/TEGDMA based composites would be reflected in a lower monomer leaching value, and this hypothesis was supported by the findings. Whether such a correlation exists within groups of UEDMA/TEGDMA based matrices having different degrees of cure was not determined and needs to be investigated in future studies. Variables such as filler composition and silane treatment did not affect the leaching values of TEGDMA in water. That finding suggests that future studies should target differences in matrices, and that the need for considering effects of filler composition and silane treatment methods should not receive the same priority.

Effect of co-monomer composition on the integrity of bioactive growth hormone released from novel PEMA based polymers.

The release of human growth hormone (hGH) from hormone loaded bone cement was previously shown to enhance osteoid formation. hGH is a complex protein and its incorporation into such cements may compromise its bioactivity. We therefore characterized the release of hGH from a series of methacrylate systems based upon poly(ethylmethacrylate) (PEMA). Different mixtures of two monomers, hydroxyethylmethacrylate (HEMA) and n-butylmethacrylate (n-BM) were used to provide polymers with graded water uptakes. Exclusive use of only one of the monomers resulted in enhanced cytotoxicity and also reduced release of the bioactive hormone. Combinations of the monomers improved the recovery of bioactivity from the polymers and reduced their cytotoxicity. hGH released from the polymer with the lowest water uptake (100% n-BM, 0% HEMA) had an exceptionally low bioactivity: immunoactivity ratio, suggesting that the bioactive site of the hormone is particularly susceptible to disruption when it is incorporated into this matrix.

Effect of the chemical structure of some hydrogels on their characteristic properties. I. Effect of comonomer composition

AbstractSome hydrogels of different chemical composition were synthesized using 2‐hydroxyethyl methacrylate, methacrylic acid, acrylic acid, and acrylamide in different ratios and crosslinked by ethylene dimethacrylate. Effects of the copolymer composition as well as the type of monomers on some hydrogel characteristics were evaluated. Some characteristic properties, namely soluble fraction percentage, swelling degree, solution uptake, and salt uptake were found to be markedly affected by the hydrogel composition.