Graft copolymerization of methyl acrylate onto nylon1010 initiated by potassium diperiodatonickelate(IV)

In this article, the graft copolymerization of methyl acrylate (MA) onto nylon1010 by using potassium diperiodatonickelate(IV) [Ni(IV)]–nylon1010 redox system as initiator was studied in alkaline medium. The effect of different factors on grafting parameters was investigated. The structure of the graft copolymer was determined by infrared (IR), X-ray diffraction, and scanning electron microscope (SEM). It was found that Ni(IV)–nylon1010 system is an efficient redox initiator for this graft copolymerization. A single-electron transfer mechanism is proposed to explain the formation of radicals and the initiation. The graft copolymer was used as the compatibilizer in blends of poly(methyl methacrylate) (PMMA) and nylon1010. The SEM photographs indicate that the graft copolymer greatly improved the compatibility of the blend. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2636–2640, 2001     

Graft copolymerization of methyl acrylate onto poly(vinyl alcohol) initiated by potassium diperiodatonickelate(IV)

The graft copolymerization of methyl acrylate onto poly(vinyl alcohol) (PVA) with a potassium diperiodatonickelate(IV) [Ni(IV)]–PVA redox system as an initiator was investigated in an alkaline medium. The grafting parameters were determined as functions of the temperature and the concentrations of the monomer and initiator. The structures of the graft copolymers were confirmed by Fourier transform infrared spectroscopy, scanning electron microscopy, X‐ray diffraction, differential scanning calorimetry, and thermogravimetric analysis. The Ni(IV)–PVA system was found to be an efficient redox initiator for this graft copolymerization. A single‐electron‐transfer mechanism was proposed for the formation of radicals and the initiation. Other acrylate monomers, such as methyl methacrylate, ethyl acrylate, n‐butyl acrylate, and n‐butyl methacrylate, were used as reductants for graft copolymerization. These reactions definitely occurred to some degree. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 87: 529–534, 2003     

Graft copolymerization of styrene onto casein initiated by potassium diperiodatonickelate (IV) in alkaline medium

A novel redox system, potassium diperiodatonickelate (Ni(IV))‐casein is used to initiate graft copolymerization of Styrene onto casein under different conditions in aqueous alkaline solution. Graft copolymers with both high grafting efficiency (>98%) and percentage of grafting(>300%) are obtained, which indicated that (Ni(IV))‐casein redox pair is an efficient initiator for this grafting. The effects of reaction parameters, such as monomer‐to‐casein weight ratio, initiator concentration, pH, time, and temperature, are investigated. A tentative initiation mechanism is proposed. The structures and properties of the graft copolymer are characterized by Fourier transform infrared Spectroscopy, X‐ray diffraction diagrams, and Scanning Electron Microscope. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4247–4251, 2006     

Ni(Ⅳ)引发丙烯酸甲酯与三元尼龙接枝共聚反应的研究

以二过碘酸合镍(Ⅳ)钾〔Ni(Ⅳ)〕为氧化剂,共聚尼龙上的弱的还原基团(酰胺基)为还原剂,组成氧化还原引发体系,于碱性介质中直接在共聚尼龙分子骨架上产生接枝点,引发丙烯酸甲酯(MA)的接枝共聚合反应,获得了较高的接枝效率(可达90%以上)。探讨了引发剂浓度、单体浓度、反应温度对接枝参数的影响,结果表明:当c〔Ni(Ⅳ)〕=8×10-4mol/L,c(MA)=1 5mol/L,θ=35℃时,接枝效率和接枝百分比可达到最高值。用红外光谱、X射线衍射、扫描电镜对接枝共聚物进行了表征,提出了建立在镍(Ⅳ)还原为镍(Ⅱ)的过程为两步单电子转移的基础之上的引发机理。将所得接枝共聚物用作尼龙/聚甲基丙烯酸甲酯体系的增容剂,通过扫描电镜分析表明:该共混体系的相容性得到一定程度的改善。     

Graft copolymerization of methyl acrylate onto poly(vinyl alcohol) initiated by potassium diperiodatoargentate(III)

The graft copolymerization of methyl acrylate onto poly(vinyl alcohol) (PVA) using potassium diperiodatoargentate(III) [Ag(III)]–PVA redox system as initiator was studied in an alkaline medium. Some structural features and properties of the graft copolymer were confirmed by Fourier‐transfer infrared spectroscopy, scanning electron microscope, X‐ray diffraction and thermogravimetric analysis. The grafting parameters were determined as a function of concentrations of monomer, initiator, macromolecular backbone (X?_n = 1750, M? = 80 000 g mol^?1), reaction temperature and reaction time. A mechanism based on two single‐electron transfer steps is proposed to explain the formation of radicals and the initiation profile. Other acrylate monomers, such as methyl methacrylate, ethyl acrylate and n‐butyl acrylate, were also used to produce graft copolymerizations. It has been confirmed that grafting occurred to some degree. Thermogravimetric analysis was performed in a study of the moisture resistance of the graft copolymer. Copyright © 2004 Society of Chemical Industry     

Graft copolymerizaztion of methyl acrylate onto chitosan initiated by potassium diperiodatocuprate (III)

A novel redox system, potassium diperiodatocuprate [Cu (III)–chitosan], was employed to initiate the graft copolymerization of methyl acrylate (MA) onto chitosan in alkali aqueous solution. The effects of reaction variables such as monomer concentration, initiator concentration, pH and temperature were investigated. By means of a series of copolymerization reactions, the grafting conditions were optimized. Cu (III)–chitosan system was found to be an efficient redox initiator for this graft copolymerization. The structures and the thermal stability of chitosan and chitosan‐g‐poly(methyl acrylate) (PMA) were characterized by infrared spectroscopy (IR) and thermogravimetric analysis (TGA). In this article, a mechanism is proposed to explain the formation of radicals and the initiation. Finally, the graft copolymer was used as the compatibilizer in blends of poly(vinyl chloride) (PVC) and chitosan. The scanning electron microscope (SEM) photographs and differential scanning calorimetry (DSC) thermograms indicate that the graft copolymer improved the compatibility of the blend. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2283–2289, 2003     

Graft copolymerization of methyl acrylate onto chitosan initiated by potassium diperiodatoargentate (III)

A novel efficient redox system—potassium diperiodatoargentate [Ag(III)]‐chitosan—was employed to initiate the graft copolymerization of methyl acrylate (MA) onto chitosan in aqueous alkali solution. The effects of reaction variables such as monomer concentration, initiator concentration, reaction time, and temperature were investigated and the grafting conditions were optimized. The structures and the thermal stability of chitosan and chitosan‐g‐PMA were characterized by infrared spectroscopy (IR) and thermogravimetric analysis (TGA). The solubility of chitosan‐g‐PMA in some mixed solvent was tested. The graft copolymer was shown to be an effective compatibilizer in blends of poly(vinyl chloride) (PVC) and chitosan. Finally, a mechanism is proposed to explain the formation of radicals and the initiation. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 799–804, 2006     

Optimized conditions for the grafting reaction of poly(methyl methacrylate) onto oil‐palm empty fruit bunch fibers

This article describes the graft copolymerization of poly(methyl methacrylate) (PMMA) onto oil‐palm empty fruit bunches (OPEFBs) with a fiber length of less than 75 μm. The graft copolymerization was carried out under a nitrogen atmosphere by a free‐radical initiation technique in an aqueous medium. Hydrogen peroxide and ferrous ions were used as a redox initiator/cocatalyst system. The PMMA homopolymer that formed during the reaction was removed from the grafted copolymers by Soxhlet extraction. Determining the effects of the reaction period, reaction temperature, and monomer concentration on the grafting percentage was the main objective, and they were investigated systematically. The optimum reaction period, reaction temperature, monomer concentration, and initiator concentration were 60 min, 50°C, 47.15 × 10^?3 mol, and 3.92 × 10^?3 mol, respectively. The maximum percentage of grafting achieved under these optimum conditions was 173%. The presence of PMMA functional groups on OPEFB and the enormous reduction of the hydroxyl‐group absorption band in PMMA‐g‐OPEFB spectra provided evidence of the successful grafting reaction. The improvement of the thermal stability of PMMA‐g‐OPEFB also showed the optimal achievement of the grafting reaction of PMMA onto OPEFB. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Thermosensitive fibres of lyocell/poly(N‐isopropylacrylamide): multiparametric analysis for studying the graft copolymerization

The thermosensitive properties of the hydrogel poly(N‐isopropylacrylamide) (pNIPAAm) together with the good mechanical properties of lyocell fibres make a combination of the two to be thought of as a smart textile. In the present study the optimal values of various parameters that control the grafting process of pNIPAAm onto lyocell fibres were determined considering the influence of the interaction between them. The copolymerization of pNIPAAm hydrogel onto lyocell fibres was performed in aqueous acidic medium using cerium(IV) as initiator. An experimental design was planned in order to study the effect of the interactions between some variables that affect the kinetics of the graft copolymerization: the cerium(IV) initiator concentration, the N‐isopropylacrylamide (NIPAAm) monomer concentration and the liquor fibre‐to‐bath ratio. The results show that the interaction between the concentrations of NIPAAm and the initiator significantly affects the degree of grafting (DG), the optimum values being 1250 and 12.25 mmol L^?1, respectively. In contrast, the liquor ratio parameter shows no significant interaction with the other two variables studied, meaning that it acts independently but showing a proportional relationship with respect to the DG obtained. In addition, the presence of pNIPAAm in the copolymer obtained was confirmed by Fourier transform infrared spectral analysis. Moreover, the water sorption capacity, depending on the temperature, of the lyocell/pNIPAAm copolymer was studied, with an increase being observed when the DG is higher than 60% and also increasing with the temperature.© 2012 Society of Chemical Industry     

Ce(IV)‐initiated graft polymerization of acrylic acid onto poly(ethylene terephthalate) fiber

Graft copolymerization of acrylic acid onto poly(ethylene terephthalate) (PET) fiber by a redox system using ceric (IV) initiator was studied with regard to various parameters of importance: acrylic acid concentration, ceric (IV) concentration, nitric acid concentration, reaction temperature, and reaction time. Based on the morphology of the PET fiber, it could be concluded that ceric (IV) in dilute nitric acid is a redox initiator for the surface graft copolymerization of the acrylic acid/PET system. The grafted PET fiber showed an increase in improved moisture regain to reach 900% at 39.5% graft yield. The dyeability with the basic dye and disperse dye significantly increased by 100 and 22%, respectively, as a result of the grafting onto PET fiber. Both tenacity and elongation gradually decreased by 51.2 and 28.9%, respectively, with increasing graft yield, which reduced the fiber service lifespan. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1952–1958, 2003     

Properties of PHMS‐g‐p [butylacrylate (BA)‐N‐hydroxyl‐methyl acrylamide (NMA)] graft copolymer emulsions

Emulsion graft copolymerization of poly(hydrogenmethylsiloxane) (PHMS) and butyl acrylate (BA) in the presence of functional comonomer N‐hydroxyl‐methyl acrylamide (NMA) was conducted by batch emulsion copolymerization to modify the properties of polysiloxane. Morphology of graft copolymer particles was characterized by transmission electron microscopy. The effect of polymerization method, PHMS content, initiator concentration, and NMA content on stability of emulsion, morphology, size of particle, and rheological properties were investigated. It has been found that stability of emulsion is better by semicontinuous emulsion polymerization than that of batch emulsion polymerization and it increased with increasing PHMS‐NMA concentration. Increasing PHMS concentration and NMA concentration, the particle size and the viscosities increase. The property of resistance to electrolytes of graft copolymer emulsions and swelling property of film were also discussed. Results showed PHMS‐g‐P [butylacrylate (BA)‐N‐hydroxyl‐methyl acrylamide (NMA)] graft copolymer emulsion has good resistance to electrolytes and the water absorption of its film increases with increasing BA‐NMA content grafted onto PHMS. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 2209–2217, 1999     

Synthesis and characterization of butyl acrylate graft sodium salt of partially carboxymethylated starch

Graft copolymers were synthesized by graft copolymerization of butyl acrylate (BA) onto sodium salt of partially carboxymethylated starch (Na‐PCMS). Ceric ammonium nitrate (CAN), a redox initiator, was used for initiation of graft copolymerization reaction. All the experiments were run with Na‐PCMS having degree of substitution, DS = 0.35. The grafting reaction was characterized by parameters such as % total conversion (%Ct), % grafting (%G), % grafting efficiency (%GE), and % add‐on. Graft copolymers were characterized by infrared spectral analysis and scanning electron microscopy. Variables affecting graft copolymerization reaction such as nitric acid concentration, reaction time, reaction temperature, and ceric ion concentration were investigated. The results revealed that 0.3M CAN as initiator, 0.3M HNO₃, with reaction time 4–4.5 h at 25–30°C were found as suitable parameters for maximum yield of graft copolymerization reaction. © 2006 Wiley Periodicals, Inc. JAppl Polym Sci 102: 3334–3340, 2006     

Chlorohydrin water swellable rubber compatibilized by an amphiphilic graft copolymer. I. Synthesis and characterization of compatibilizer PVA‐g‐PBA

The graft copolymerization of butyl acrylate onto poly(vinyl alcohol) with ceric ammonium nitrate as redox initiator in a aqueous medium has been investigated. The formation of graft copolymer was confirmed by means of IR, scanning electron microscopy (SEM), and wide‐angle X‐ray diffraction (WAXD). The percentage of mononer conversion and percentage of grafting varied with concentrations of initiator, nitric acid, monomer, macromolecular backbone (X_n = 1750, M = 80 000), reaction temperature and reaction time. Some inorganic salts and organic solvents have a great influence upon grafting. The reaction mechanism has been explored, and rate equations for the reaction are established. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 977–986, 2000     

Modified chitosan. I. Optimized cerium ammonium nitrate‐induced synthesis of chitosan‐graft‐polyacrylonitrile

Chitin was extracted from shrimp shells and then deacetylated to obtain chitosan. The degree of deacetylation of the chitosan was determined to be 0.76 using pH‐metric titration. A large number of cyanide functional groups were introduced onto chitosan by grafting with polyacrylonitrile as an efficient way of modification. The graft copolymerization reactions were carried out under argon atmosphere in a homogeneous aqueous phase (containing a small portion of acetic acid) by using ceric ammonium nitrate as an initiator. Evidence of grafting was obtained by comparing FTIR spectra of chitosan and the graft copolymer as well as solubility characteristics of the products. The synthetic conditions were systematically optimized through studying the influential factors, including temperature and concentrations of the initiator, acrylonitrile monomer (AN), acetic acid, and chitosan. The effect of individual factors was investigated by calculating and monitoring the variations of the grafting parameters [i.e., grafting ratio (Gr), grafting efficiency (Ge), add‐on value (Ad), homopolymer content (Hp), and total conversion (Ct)]. Under optimum conditions, the grafting parameters were achieved as 535, 98, 81, 2, and 102%, respectively. A mechanism for the free‐radical grafting was proposed. As empirical rates of polymerization and graft copolymerization were plotted against [AN] and [Ce⁴⁺]^1/2, the experimental kinetic data displayed a good match to a reported rate statement. The overall activation energy for the graft copolymerization was determined to be 44.9 kJ/mol. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 2048–2054, 2003     

Synthesis of polyacrylamide with pendant poly(n‐octyl acrylate) chains using macromer technique and studies on their properties

An amphiphilic graft copolymer of polyacrylamide (PAM) with uniform poly(n‐octyl acrylate) (POA) grafts was synthesized by copolymerization of AM with POA macromer in solution using azobisisobutyronitrile as the initiator. The macromer was synthesized by free radical polymerization of octyl acrylate in the presence of different amounts of thioglycolic acid as the chain transfer agent, followed by termination with glycidyl methacrylate. The reactivity ratio and effects of copolymerization conditions on the conversion of macromer or grafting efficiency were studied. The crude products were purified by extraction with toluene and water successively. The purified graft copolymer was characterized by IR, DSC, and TEM. PAM‐g‐POA can bring about microphase separation and exhibits good emulsifying properties and water absorbency. PAM‐g‐POA exhibits a very good compatibilizing effect on the acrylic rubber/poly(vinyl chloride) blends. About 2–3% of the graft copolymer is enough for enhancing the tensile strength of the blends. The tensile strength of the blends is more than twice that without the compatibilizer. DSC and SEM demonstrated the enhancement of compatibility in the presence of the graft copolymer. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Synthesis of a cellulose‐grafted polymeric support and its application in the reductions of some carbonyl compounds

The reduction of carbonyl compounds by borohydride supported on a cellulose–anion exchange resin is known. The synthesis of a graft copolymer of cellulose and poly(4‐vinyl pyridine) [CellO‐g‐poly(4‐VP)] has been carried out with ceric ions as a redox initiator. A postgrafting treatment of CellO‐g‐poly(4‐VP) with sodium borohydride has produced CellO‐g‐poly(4‐VP) borane, a polymer‐supported reducing agent. Optimum conditions pertaining to the maximum percentage of grafting have been evaluated as a function of the concentrations of the initiator, monomer, and nitric acid, amount of water, time, and temperature. The maximum percentage of grafting (585%) has been obtained with 0.927 mol/L of 4‐vinyl pyridine and 0.018 mol/L of ceric ammonium nitrate in 120 min at 45°C. The polymeric support, CellO‐g‐poly(4‐VP) borane, has been used for reduction reactions of different carbonyl compounds such as benzaldehyde, cyclohexanone, crotonaldehyde, acetone, and furfural. The graft copolymer has been characterized with IR and thermogravimetric analysis. The grafted cellulose has been found to be thermally stable. The reduced products have been characterized with IR and NMR spectral methods. The reagent has been reused for the reduction of a fresh carbonyl compound, and it has been observed that the polymeric reagent reduces the compounds successfully but with a little lower product yield. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Graft copolymerization of acrylic acid onto cellulose: Effects of pretreatments and crosslinking agent

The graft copolymerization of acrylic acid (AA) and 2‐acrylamido 2‐methylpropane sulfonic acid (AASO₃H) onto cellulose, in the presence or absence of crosslinking agent N,N′‐methylene bisacrylamide (NMBA), by using different concentrations of ceric ammonium nitrate (CAN) initiator in aqueous nitric acid solution at either 5 or 30°C was investigated. To investigate the effect of pretreatment of cellulose on the copolymerization, before some grafting reactions cellulose was pretreated with either 2 or 20 wt % NaOH solutions or heated in distilled water/aqueous nitric acid (2.5 × 10^?3 M) at 55°C. To determine how the excess of initiator affects the grafting and homopolymerization, separate reactions were carried out by removing the excess of ceric ions by filtration of the mixture of initiator solution and cellulose before the monomer addition. Extraction‐purified products were characterized by grafting percentage and equilibrium swelling capacity. Pretreatment of cellulose with NaOH solutions decreased the grafting percentage of copolymers. In the case of AA–AASO₃H mixtures, nonpretreated cellulose gave a higher grafting percentage than NaOH‐pretreated cellulose. Filtration also lowered the grafting of AA on the cellulose in the cases of pretreatment with either water or nitric acid. Copolymers with the highest grafting percentage (64.8%) and equilibrium swelling value (105 g H₂O/g copolymer) were obtained in grafting reactions carried out in the presence of NMBA at 5°C. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 2267–2272, 2001     

Phase‐transfer‐agent‐aided polymerization and graft copolymerization of acrylamide

The use of phase‐transfer catalysts, with water‐insoluble initiators, for polymerization and graft copolymerization reactions was explored. The polymerization of a water‐soluble vinyl monomer, acrylamide (AAm), and the graft copolymerization of AAm onto a water‐insoluble polymer backbone, isotactic polypropylene (IPP), with a water‐insoluble initiator, benzoyl peroxide (BPO), and a phase‐transfer catalyst, tetrabutyl ammonium bromide (Bu₄N⁺Br^?), were carried out in a water/xylene binary solvent system. The conversion percentage of AAm into polyacrylamide (PAAm) and the percentage of grafting of AAm onto IPP were determined as functions of various reaction parameters, such as the BPO, AAm, and phase‐transfer‐catalyst concentrations, the amounts of water and xylene in the water/xylene mixture, the time, and the temperature. The graft copolymer, IPP‐g‐PAAm, was characterized with IR spectroscopy and thermogravimetric analysis. By a comparison of the results of the phase‐transfer‐catalyzed graft copolymerization of AAm onto IPP and the preirradiation method, it was observed that the optimum reaction conditions were milder for the phase‐transfer‐catalyst‐aided graft copolymerization. Milder reaction conditions, including the temperature, the time of reaction, and a moderate initiator (BPO), in comparison with high‐energy γ‐rays, led to better quality products, and the reaction proceeded smoothly with high productivity. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2364–2375, 2004     

Graft copolymerization of methoxypoly(ethylene glycohol) methacrylate onto polyacrylonitrile and evaluation of nonthrombogenicity of the copolymer

Methoxypoly(ethylene glycohol) methacrylate was grafted onto polyacrylonitrile in dimethylsulfoxide solution via thioamide formation, where ammonium peroxydisulfate was used as an initiator. Optimum conditions for the graft copolymerization, such as degree of thioamidation of the trunk polymer, feeding concentration of the acrylate and the trunk polymer, and temperature were examined. Also the rate of graft polymerization was found to be proportional to concentrations of the acrylate and the trunk polymer. An increase of the degree of the grafting increased water content of the graft copolymer and decreased interfacial free energy between the copolymer and water. In vivo tests showed that the graft copolymer obtained was highly nonthrombogenic.     

Study of methyl‐methacrylate‐viscose fiber graft copolymerization and the effect of grafting on thermal properties

The graft copolymerization of methyl‐methacrylate onto viscose fibers was studied under photoactive conditions with visible light using Ce⁴⁺/Ti³⁺ combination as redox initiator in a limited aqueous medium. Polymerization conducted in the presence of light at 30 ± 1°C produced significant grafting, compared with that conducted in the dark under the same conditions. The % grafting, % total conversion, and % grafting efficiency were studied by varying time, monomer concentration, initiator concentration, and pH of the medium. The mechanism of polymerization and graft copolymer formation have been discussed. Characterization of the grafted fibers was done by Fourier transform infrared spectroscopy and scanning electron microscopy. The effect of % grafting on thermal properties was studied by thermogravimetric analysis. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 135–140, 1999