Graft Copolymerization Reaction Research Articles

Adsorption and Equilibrium Isotherm Study of Removal of Copper (II) Ions from Aqueous Solution by Chemically Modified Abelmoschus esculentus Fibers

The present study explores surface modification of Abelmoschus esculentus by graft copolymerization reaction using acrylonitrile as a monomer and ascorbic acid/H2O2 as a redox initiator. Further, polyacrylonitrile grafted fibers were treated with hydroxylamine to convert the nitrile group of the grafted fiber into the amidoxime group to enhance adsorption of copper ions from wastewater. The graft copolymers and amidoximated fibers were characterized by FT-IR and FE-SEM. The effects of physicochemical parameters such as pH of the solution, initial metal ion concentration, and time on Cu(II) adsorption were studied to optimize condition for maximum adsorption. In addition, Langmuir, Freundlich, and Tempkin models were applied to describe the adsorption isotherm of Cu2+ ions.

A novel initiating system for wool grafting

This paper describes a new method for the grafting of methacrylic acid (MAA) and other acrylic monomers onto wool fabric in aqueous medium. The novelty principally concerns the chemical approach of the redox grafting reaction that was carried out in the presence of sodium perborate (SPB) initiator. Before the grafting reaction was started, the wool fabric was treated first with a freshly prepared ferrous ammonium sulfate (FAS) solution. The so-treated fabric formed, with SPB, an efficacious redox system capable of initiating grafting of methacrylic acid (MAA) and other acrylic monomers onto the wool fabric. The effect of the polymerization conditions on the polymer criteria, namely, graft yield (%GY), homopolymer (%HP), total conversion (%TC), and grafting efficiency (%GE), was studied. These polymer criteria were found to depend spaciously upon concentrations of the Fe2+ ion (activator), SPB (initiator), and MAA, pH of the polymerization medium, duration and temperature of polymerization. The graft copolymerization reaction has also been carried out in the presence of polymerization activators (e.g. reductant transition metal ions) and an inhibitor (e.g. hydroquinone). A suitable mechanism for the grafting processes has been suggested, in accordance with the experimental results.

Synthesis and properties of collagen-g-poly(sodium acrylate-co-2-hydroxyethylacrylate) superabsorbent hydrogels

Novel biopolymer-based superabsorbent hydrogels were prepared by grafting crosslinked poly(acrylic acid-co-2-hydroxyethyl acrylate) (PAA-co-PHEA) chains onto collagen backbones through a free radical polymerization method. The graft copolymerization reaction was carried out in a homogeneous medium and in the presence of ammonium persulfate (APS) as initiator and N,N '-methylene bisacrylamide (MBA) as crosslinker. A proposed mechanism for collagen-g-(PAA-co-PHEA) formation was suggested and the hydrogel structure was confirmed using FTIR spectroscopy and TGA thermal analysis. Moreover, the morphology of the samples was examined by scanning electron microscopy (SEM). The effect of concentration of MBA as well as AA/HEA weight ratio on the swelling capacity of the hydrogel was also studied. Furthermore, the water absorbency of hydrogels was measured in solutions with pH ranging 1 to 13. The collagen-based hydrogel exhibited a pH-responsive character, so that a swelling-deswelling pulsatile behavior was recorded at pHs 2 and 8. Preliminary swelling and deswelling behaviors of the hydrogels were also studied. Additionally, the hydrogels exhibited salt-sensitivity and cation exchange properties.

Study of Irradiation Hydrophilic Modification of Polypropylene Meltblown Nonwovens

In this paper, we took the co-irradiation technology, use the high-energy beam irradiate the polypropylene meltblown nonwovens which soaked with acrylic acid, so that the graft copolymerization reaction was occurred between the acrylic and the polypropylene, the influence of acrylic acid concentration and the irradiation dose to the hydrophilic properties and breaking strength were studied. The results shows that when the monomer concentration was between 2% and 8% and the irradiation dose was between 10kGy and 50 kGy, the hydrophilic properties increased with the increasing of the monomer concentration and irradiation dose. But the breaking strength wasn’t affected.

Synthesis and Characterization of Comb-Like Polycarboxylate Superplasticizer

Polycarboxylate superplasticizers have become the superstar for high-performance concrete. Because their molecular structure can be easily manipulated by impart new materials to acquire new performance. In this paper, the synthetic parameters adjusting experiment is utilized to get the optimal synthetic formulations. The reaction control factors and polymerization mechanism are also discussed. After characterization, we concluded that the expected performance of polycarboxylate superplasticizer could fabricate through radical graft copolymerization reaction by molecular designing.

Preparation and Investigation on Swelling and Drug Delivery Properties of a Novel Silver/Salep-g-Poly(Acrylic Acid) Nanocomposite Hydrogel

Novel silver/salep-g-poly(acrylic acid) nanocomposite hydrogel were prepared in aqueous solution using poly(acrylic acid) grafted onto salep as a biopolymer based material. FT-IR spectra confirmed that poly(acrylic acid) (PAA) had been grafted onto salep in graft copolymerization reaction. TEM observations showed that silver nanoparticles have been uniformly dispersed in polymeric matrix. Effects of pH, acrylic acid (AA) amount and silver ion concentration on swelling capabilities were investigated. Results indicate that modifying AA and silver ion can improve swelling properties of the resultant nanocomposite hydrogel. pH response of this nanocomposite hydrogel in acidic and neutral pH made it suitable for drug delivery applications.

A pH-Sensitive Biopolymer-Based Superabsorbent Nanocomposite from Sodium Alginate and Attapulgite: Synthesis, Characterization, and Swelling Behaviors

Graft copolymerization reaction among sodium alginate (NaAlg), sodium acrylate (NaA), and nanoscale attapulgite (APT) was performed to fabricate a novel pH-sensitive NaAlg-g-PNaA/APT superabsorbent nanocomposite. FTIR spectra proved NaA monomers were grafted onto NaAlg backbone and APT participated in polymerization. FESEM, TEM, and TGA analyses revealed the better dispersion of APT fibrils in the matrix and the improved thermal stability. The swelling capacity and rate of the superabsorbent was clearly enhanced after introducing APT. The external salts and surfactants showed greater influence on the swelling behaviors. The nanocomposite exhibited reversible On-Off pH-sensitivity between pHs 2.0 and 7.4, and the intriguing pH-triggered deswelling behavior in various polyvinylperrodone (PVP) solutions was observed.

Enhancing water resistance of paper by graft copolymerization reaction

AbstractThe chemical graft copolymerization reactions were used to enhance water resistance of paper by reaction of acrylonitrile (AN) monomer onto cellulosic paper sheet in the presence of comonomer (styrene or acrylic acid or itaconic acid) 1 : 1 molar ratio in dimethyl formamide using benzoyl peroxide as free radical initiator under nitrogen atmosphere at 70°C. The infrared spectroscopy confirms that graft copolymerization reaction occurs onto the paper samples. Water absorption test was carried out following the Normal Protocol 7/81 (water absorption by complete immersion) to evaluate the protective effect of the graft treatment onto the paper sheet. It was found that the three graft copolymerization systems reduced the water absorption of the investigated paper and the reduction of water absorption is directly proportional to the grafting %. The wettability of the grafted and ungrafted paper sheet samples were investigated using the wicking time method which exhibits the decreasing of paper sheet wettability using the AN/S comonomers in the graft copolymerization reaction. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Synthesis and thermal properties of poly(styrene-co-ally alcohol)-graft-stearic acid copolymers as novel solid–solid PCMs for thermal energy storage

A series of poly(styrene-co-allyalcohol)-graft-stearic acid copolymers were synthesized as novel polymeric solid–solid phase change materials (SSPCMs). The graft copolymerization reactions between poly(styrene-co-allyalcohol) and stearoyl chloride were verified by Fourier transform infrared (FT-IR) and Proton Nuclear Magnetic Resonance (1H NMR) spectroscopy techniques. The crystal morphology of the SSPCMs was investigated using polarized optical microscopy (POM) technique. Thermal energy storage properties of the synthesized SSPCMs were measured using differential scanning calorimetry (DSC) analysis. The POM results showed that the crystalline phase of the copolymers transformed to amorphous phase above their phase transition temperatures. Thermal energy storage properties of the synthesized SSPCMs were investigated by differential scanning calorimetry (DSC) and found that they had typical solid–solid phase transition temperatures in the range of 27–30°C and high latent heat enthalpy between 34 and 74J/g. Especially, the copolymer with the mole ratio of 1/1 (poly(styrene-co-allyalcohol)/stearoyl chloride) is the most attractive one due to the highest latent heat storage capacity among them. The results of DSC and FT-IR analysis indicated that the synthesized SSPCMs had good thermal reliability and chemical stability after 5000 thermal cycles. Thermogravimetric (TG) analysis results suggested that the synthesized SSPCMs had high thermal resistance. In addition, thermal conductivity measurements signified that the synthesized PCMs had higher thermal conductivity compared to that of poly(styrene-co-allyalcohol). The synthesized copolymers as novel SSPCMs have considerable potential for thermal energy storage applications such as solar space heating and cooling in buildings and greenhouses.

Stimuli-responsive membranes through peroxidation radiation-induced grafting of 2-hydroxyethyl methacrylate (2-HEMA) onto isotactic polypropylene film (IPP)

Stimuli-responsive membranes were prepared by peroxidation radiation-induced grafting of 2-hydroxyethyl methacrylate (2-HEMA) onto IPP. The radioactive isotope 60Co was used as the source of gamma radiation. A plausible mechanism of grafting has been proposed. Using this method, the degree of grafting and morphology could be controlled through the variation of reaction parameters such as total dose, inhibitor concentration, monomer concentration, reaction time, reaction temperature and solvents. Maximum percentage of grafting (210 %) was obtained at total radiation dose of 20 kGy. The graft copolymerization reaction was carried out for 3 h with 20 v/v% of the monomer (2-HEMA) in methanol at 85 °C using 0.06 wt% of FeCl3 as inhibitor. The chemical structures of grafted membranes were characterized by Fourier transform infrared spectroscopy (FTIR) which indicates that HEMA has been grafted onto IPP. The atomic force microscopy (AFM), scanning electron microscopy (SEM) techniques were used to assess the morphological characterization of the membranes, revealing the roughness of the surface. These membranes were investigated for their swelling behavior. pH-sensitivity and the dyeability of the grafted and ungrafted membranes have also been studied.

Synthesis, characterization, and thermal degradation of new aromatic poly(azomethine-urethane)s and their polyphenol derivatives

A new polyurethane was synthesized by condensation reaction of 2,4-dihydroxy benzaldehyde (DHB) with methylene-di-p-phenyl-diisocyanate (MDI) under argon atmosphere. The synthesized polyurethane was converted to its poly(azomethine urethane) species (MP-2AP, MP-3AP, and MP-4AP) by graft copolymerization reactions with amino phenols (2-amino phenol, 3-amino phenol, and 4-amino phenol). Obtained poly(azomethine urethane)s (PAMUs) were converted to their polyphenol species (P-MP-2AP, P-MP-3AP, and P-MP-4AP) by oxidative polymerization reaction (OP) using NaOCl as the oxidant. The structures of the obtained compounds were confirmed by FT-IR, UV–vis, 1H-NMR, and 13C-NMR techniques. The molecular weight distribution parameters of the synthesized compounds were determined by the size exclusion chromatography (SEC). The synthesized compounds were also characterized by solubility tests, TG-DTA, and DSC analyses. Thermal decomposition steps at various temperatures were clarified by FT-IR analyses of degraded products. Fluorescence measurements were carried out in various concentrated DMF solutions to determine the optimum concentrations to obtain the maximal PL intensities.

Synthesis, characterization, and thermal stability of novel poly(azomethine-urethane)s and polyphenol derivatives derived from 2,4-dihydroxy benzaldehyde and toluene-2,4-diisocyanate

Up to date, only a few kinds of poly(azomethine-urethane)s (PAMUs) were synthesized and studied with thermal degradation steps. However, polyphenol based PAMUs including azomethine linkages have not been investigated yet. The polyurethanes were prepared by condensation reaction of 2,4-dihydroxybenzaldehyde (2,4-DHBA) with toluene-2,4-diisocyanate (TDI) under argon atmosphere. Synthesized polyurethane was converted to its poly(azomethine urethane) species (TP-2AP, TP-3AP, and TP-4AP) by graft copolymerization reactions with amino phenols (2-amino phenol, 3-amino phenol, and 4-amino phenol). Obtained poly(azomethine urethane)s were converted to their polyphenol species (P-TP-2AP, P-TP-3AP, and P-TP-4AP) by oxidative polymerization reaction (OP) using NaOCl as the oxidant. The structures of the obtained compounds were confirmed by FT-IR, UV–vis, 1H NMR, and 13C NMR techniques. The molecular weight distribution parameters of the synthesized compounds were determined by the size exclusion chromatography (SEC). The synthesized compounds were also characterized by solubility tests, TG-DTA, and DSC. Fluorescence measurements were carried out in various concentrated DMF solutions to determine the optimum concentrations to obtain the maximal PL intensities.

Poly(acrylic acid)-modified poly(glycidylmethacrylate)-grafted nanocellulose as matrices for the adsorption of lysozyme from aqueous solutions

In this study, a cellulose based hydrogel, poly(acrylic acid)-modified poly(glycidylmethacrylate)-grafted nanocellulose (PAPGNC) was synthesized by graft copolymerization reaction of glycidylmethacrylate onto nanocellulose (NC) in the presence of ethyleneglycoldimethacrylate as cross-linker followed by immobilization of poly(acrylic acid). The hydrogel was characterized using thermogravimetric (TG) analysis, X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) analyses. The efficiency of PAPGNC to adsorb chicken egg white lysozyme (LYZ) from aqueous solutions was studied. LYZ exhibited a decrease in α-helix and increase in β-structure, upon immobilization onto PAPGNC. The maximum adsorption was found to be at pH 6.0 and adsorption capacity attained saturation within 2h. The kinetic data were found to follow pseudo-second-order model which is based on chemisorption. The well agreement of equilibrium data with Langmuir and Jovanovic isotherm models confirm the monolayer coverage of LYZ onto PAPGNC surface. The maximum adsorption capacity based on Langmuir isotherm model was found to be 148.42mg/g at 30°C. Thermodynamic study revealed an endothermic adsorption process. Spent adsorbent was effectively degenerated with 0.1M NaSCN. The present investigation shows that PAPGNC is a promising material for the recovery of LYZ from aqueous solutions.

APS-initiated graft copolymerization of N-Vinyl pyrollidone onto gelatin: Preparation, characterization, and optimization of grafting parameters

In this work, large numbers of hydrophilic functional groups were introduced onto gelatin by grafting with N-vinyl pyrollidone monomer. The graft copolymerization reactions were carried out under nitrogen atmosphere using ammonium persulfate (APS) as an initiator. The graft copolymer was characterized by Fourier transform infrared spectra, thermo-gravimetric analysis and solubility test. The existence of a sharp intense peak at 1653 cm-1 in FTIR spectra of the graft copolymer, improvement of the thermal stability of gelatin-based copolymer and the solubility difference of the copolymer and the homopolymer prove the formation of graft copolymer. The effects of reaction variables, such as concentration of the initiator, monomer and gelatin, as well as, reaction temperature and time were investigated and the grafting conditions were optimized. The optimum reaction conditions resulting in maximum grafting ratio and add-on value have been determined. Key words: Gelatin, N-vinyl pyrollidone, graft copolymerization, ammonium persulfate.

Synthesis and thermal properties of polystyrene-graft-PEG copolymers as new kinds of solid–solid phase change materials for thermal energy storage

A series of polystyrene-graft-PEG6000 copolymers were synthesized as new kinds of polymeric solid–solid phase change materials (SSPCMs). The synthesized SSPCMs storage latent heat as the soft segments PEG6000 of the copolymers transform from crystalline phase to amorphous phase and therefore they can keep its solid state during the phase transition processing. The graft copolymerization reaction between polystyrene and PEG was verified by Fourier transform infrared (FT-IR) and 1H NMR spectroscopy techniques. The morphology of the synthesized SSPCMs was characterized by polarization optical microscopy (POM). Thermal energy storage properties, thermal reliability and thermal stability of the synthesized SSPCMs were investigated by differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis methods. The DSC results showed that the synthesized SSPCMs had typical solid–solid phase transition temperatures in the range of 55–58°C and high latent heat enthalpy in the range of 116–174Jg−1. The TG analysis findings showed that the synthesized SSPCMs had high thermal durability above their working temperatures. Also, thermal conductivity measurements indicated that the synthesized PCMs had higher thermal conductivity compared to that of polystyrene. The synthesized polystyrene-graft-PEG6000 copolymers as new kinds of SSPCMs could be used for thermal energy storage.

A highly efficient carboxyl-terminated hybrid adsorbent composite matrix for the adsorption of uranium(VI) and thorium(IV) from aqueous solutions and nuclear industry effluents

ABSTRACT A novel hybrid adsorbent composite matrix, polymethacrylic acid-grafted chitosan/bentonite (PMAA-g-CTS/B) was prepared through graft copolymerization reaction of methacrylic acid and chitosan in the presence of bentonite and N,N’- methylenebisacrylamide as cross linker. The composite was characterized using FTIR, XRD, XPS, surface area analyzer and Zeta potential measurements. Batch experiments were conducted to evaluate the efficiency of PMAA-g-CTS/B for the removal of U(VI) and Th(IV) from aqueous solutions. The adsorption behavior of the composite towards U(VI) and Th(IV) from simulated nuclear industry wastewater and seawater was studied using batch process. The adsorption behavior of PMAA-g-CTS/B towards U(VI) and Th(IV) from water and sea water was studied under varying operating conditions of pH, concentration of U(VI) and Th(IV), contact time, and temperature. The effective range of pH for the removal of U(VI) and Th(IV) was 5.0−6.0. Kinetic data followed a pseudo-second-order model. The equilibrium data were correlated with the Langmuir isotherm model. The equilibrium sorption capacity was estimated to be 117.2 for U(VI) and 110.5 mg/g for Th(IV) at 30°C. Adsorption-desorption experiments over four cycles illustrate the feasibility of the repeated uses of this composite for the extraction of U(VI) and Th(IV) from aqueous solutions. The finding of the investigation showed that the composite exhibits high adsorption capacity for U(VI) as well as Th(IV) ions.

In-Air Graft Copolymerization of Ethyl Acrylate onto Natural Cellulosic Polymers

The present work deals with the graft copolymerization of ethyl acrylate (EA) onto lignocellulosic natural fibers of the Himalayan region in air in the presence of potassium persulfate (KPS) as initiator. Raw fibers and the graft copolymers after the completion of copolymerization reaction were subjected to evaluation of different properties. Correlation of physicochemical properties with the graft copolymerization reaction mechanism is discussed. Characterization of the graft copolymers was carried out with scanning electron microscopy, Fourier transform-infrared spectrophotometry, and thermogravimetric analysis.

Preparation, characterization and adsorption behavior of tannin-modified poly(glycidylmethacrylate)-grafted zirconium oxide-densified cellulose for the selective separation of bovine serum albumin

Bovine serum albumin (BSA) is one of the major constituents of blood plasma and its recovery is a significantly useful subject for biomedical applications. In this study, a novel adsorbent, tannin-modified poly(glycidylmethacrylate)-grafted zirconium oxide-densified cellulose (TMPGZDC) was synthesized by graft copolymerization reaction of glycidylmethacrylate onto zirconium oxide-densified cellulose (ZDC) in the presence of N,N′-methylenebisacrylamide as cross-linker followed by tannin immobilization. The adsorbent was characterized using TG, XRD, SEM/EDS, FTIR and fluorescence analyses. The efficiency of the TMPGZDC to adsorb BSA from aqueous solutions was studied at different optimized conditions. The optimum pH for maximum adsorption was found to be 4.8 with the adsorption percentage of 97.8% for an initial concentration of 100mg/L. Equilibrium was achieved within 30min. The kinetic data were found to follow pseudo-first-order model which is based on solid capacity. The well agreement of equilibrium data with Langmuir isotherm and Redlich–Peterson isotherm models confirms the monolayer coverage of BSA onto TMPGZDC surface and the maximum adsorption capacity at 30°C was found to be 93.11mg/g. Thermodynamic study revealed an exothermic adsorption process. TMPGZDC was found to be efficient in the selective adsorption of proteins. Spent adsorbent was effectively degenerated with 0.1M NaCl. The present investigation shows that TMPGZDC is a promising adsorbent for the recovery of BSA from aqueous solutions and protein mixtures.

Preparation and adsorption properties of a novel interpenetrating polymer network (IPN) containing carboxyl groups for basic dye from aqueous media

A novel hybrid hydrogel of interpenetrating polymer networks (IPNs) was synthesized by the graft copolymerization reaction among cellulose (Cell), polymethacrylic acid (PMAA) and bentonite (Bent), in the presence of N,N’-methylenebisacrylamide (MBA) as a cross linker and potassium peroxydisulphate (K2S2O8) as an initiator. The structural and morphological characterizations of this IPN, polymethacrylic acid grafted cellulose/bentonite composite (PMAA-g-Cell/Bent), were done using FTIR, XRD, and TGA. The resulting IPN was used as an adsorbent for studying the effectiveness in the removal of methylene blue (MB), which is having a wide range of use in different fields such as biology and chemistry. The effects of contact time, initial sorbate concentration, pH, dose of adsorbent and temperature were studied to optimize the adsorption capacity. The batch sorption technique employed, revealed a maximum adsorption of 99.9% at pH 6.5. Three kinetic models including pseudo-first-order, pseudo-second-order, and intraparticle diffusion models were selected to follow the adsorption processes. The adsorption of MB onto PMAA-g-Cell/Bent could be best described by the pseudo-second-order equation. Adsorption isotherm of MB onto PMAA-g-Cell/Bent was determined and correlated with common isotherm equations such as Langmuir, Freundlich and Sips isotherms. The equilibrium data for MB adsorption well fitted to the Sips adsorption isotherm having R2 value 0.999 and 1/n, 0.33. Thermodynamic parameters explain that the adsorption process is exothermic in nature and it is a spontaneous process. This novel IPN exhibited excellent performance in MB adsorption. Desorption of MB was studied using 0.1M HCl. Adsorption/desorption experimental results further proved that the material has sustainable stability over repeated MB loading and stripping. The investigations demonstrated that the PMAA-g-Cell/Bent can be based as an efficient adsorbent for the removal of MB from water and wastewater.

Cationic Gelatin Graft Copolymers: Synthesis, Characterization and Application

A novel cationic gelatin graft copolymer was developed by the graft copolymerization reaction of gelatin with acrylamide (AM) and methacryloyloxyethyl trimethylammonium chloride (DMC) in this paper. The structure of graft copolymer was analyzed briefly by the analysis of infrared spectrum, and it was found that monomers (AM and DMC) actually were grafted onto the backbone of gelatin. The effect of reaction conditions such as the weight ratios of AM/gelatin or AM/DMC on grafting parameters and the application of the cationic graft copolymer as the dry strength agent in papermaking were investigated. Experiments showed that a graft copolymer with high the percent grafting and the grafting efficiency could be obtained by controlling the AM/gelatin weight ratio and AM/DMC weight ratio. The application test showed that the results obtained from the physical intensities of handsheets under the treatment of the grafted gelatin [gel-g-P(AM-co-DMC)] were great better than the control sample, which was due to the hydrogen bonds and ionic bonds among fibres in pulp and cationic graft copolymer.