Graft copolymerization of acrylonitrile and methyl methacrylate monomer mixtures on crumb natural rubber

Graft copolymerization of mixtures of acrylonitrile and methyl methacylate on crumb natural rubber was carried out in toluene at 60°C. The nitrogen content of the grafted copolymer was determined by elemental analysis and used to estimate the composition of the copolymer samples. It was found that the amount of acrylonitrile monomeric units incorporated into the polymer was disproportionately lower than the acylonitrile content of the feed and explanations in terms of the e‐value of the monomers and the inherent heterogenous nature of the polymerization mixture were offered. The miscibility of the natural rubber‐g‐polyacrylonitrile‐co‐poly(methyl methacrylate) with poly(vinyl chloride) was studied by viscometry, differential scanning calorimetry, and phase contrast microscopy. It was found that the natural rubber‐g‐polyacrylonitrile‐co‐poly(methyl methacrylate) formed semimiscible blends with poly(vinyl chloride). © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1872–1877, 2002; DOI 10.1002/app.10474     

Graft polymerization of vinyl acetate onto starch. Saponification to starch–g–poly(vinyl alcohol)

Graft polymerizations of vinyl acetate onto granular corn starch were initiated by cobalt-60 irradiation of starch-monomer-water mixtures, and ungrafted poly(vinylacetate) was separated from the graft copolymer by benzene extraction. Conversions of monomer to polymer were quantitative at a radiation dose of 1.0 Mrad. However, over half of the polymer was present as ungrafted poly-(vinyl acetate) (grafting efficiency less than 50%), and the graft copolymer contained only 34% grafted synthetic polymer (34% add-on). Lower irradiation doses produced lower conversions of monomer to polymer and gave graft copolymers with lower % add-on. Addition of minor amounts of acrylamide, methyl acrylate, and methacrylic acid as comonomers produced only small increases in % add-on and grafting efficiency. However, grafting efficiency was increased to 70% when a monomer mixture containing about 10% methyl methacrylate was used. Grafting efficiency could be increased to over 90% if the graft polymerization of vinyl acetate-methyl methacrylate was carried out near 0°C, although conversion of monomers to polymer was low and grafted polymer contained 40-50% poly(methyl methacrylate). Selected graft copolymers were treated with methanolic sodium hydroxide to convert starch–g–poly(vinyl acetate) to starch–g–poly(vinyl alcohol). The molecular weight of the poly(vinyl alcohol) moiety was about 30,000. The solubility of starch–g–poly(vinyl alcohol) in hot water was less than 50%; however, solubility could be increased by substituting either acid-modified or hypochlorite-oxidized starch for unmodified starch in the graft polymerization reaction. Vinyl acetate was also graft polymerized onto acid-modified starch which had been dispersed and partially solubilized by heating in water. A total irradiation dose of either 1.0 or 0.5 Mrad gave starch–g–poly(vinyl acetate) with about 35% add-on, and a grafting efficiency of about 40% was obtained. A film cast from a starch–g–poly(vinyl alcohol) copolymer in which homopolymer was not removed exhibited a higher ultimate tensile strength than a comparable physical mixture of starch and poly(vinyl alcohol).     

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     

Mechanochemical block copolymerization of poly(vinyl chloride) with methyl methacrylate by ultrasonic irradiation

Summary Mechanical degradation and mechanochemical block copolymerization in systems of poly(vinyl chloride)-methyl methacrylate-solvents have been studied by ultrasonic irradiation at 60°C. The effect of the concentrations of poly(vinyl chloride) on mechanical degradation was investigated. In addition, the effects of poly(vinyl chloride) and methyl methacrylate concentrations on mechanochemical block copolymerization were investigated. The rate equation for mechanochemical block copolymerization has been deduced, and the experimental results were in fairly good agreement with the equation. The changes in the composition of the block copolymer and homopolymers in the reaction products were followed by turbidimetric titration.     

Poly(vinyl alcohol) fiber radicals induced by photo-irradiation at room temperature

The decay behavior of radicals produced on poly(vinyl alcohol) (PVA) fiber by photo-irradiation at room temperature and the graft copolymerization of methyl methacrylate (MMA) on the irradiated PVA fiber were investigated. Two kinds of stable radicals showing singlet and triplet spectra were indicated for both unsensitized and ferric ion-sensitized samples, especially with the emphasis of triplet component radical. The decay of radicals was promoted by contact with various organic solvent-water solutions, which effects were in the order of dimethyl sulfoxide (DMSO)–water > acetone–water > water > dioxane–water > methanol–water. On the other hand, graft copolymerization of MMA on the preirradiated sample was effectively initiated with the aid of a little water or a mixed solution of organic solvent and water. Methanol and dioxane, which decay radicals milder than acetone and DMSO do, contributed to give a higher per cent grafting. As no initiation took place with the unirradiated sample, it is concluded that the ability of preirradiated samples to initiate graft copolymerization should be caused by the PVA fiber radicals, which are smoothly produced by photo-irradiation at room temperature and show a triplet spectrum.     

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     

Synthesis and characterization of poly(vinyl chloride‐co‐vinyl acetate)‐graft‐poly[(meth)acrylates] by atom transfer radical polymerization

The graft polymerization of methyl methacrylate and butyl acrylate onto poly(vinyl chloride‐co‐vinyl acetate) with atom transfer radical polymerization (ATRP) was successfully carried out with copper(I) thiocyanate/N,N,N′,N′,N″‐pentamethyldiethylenetriamine and copper(I) chloride/2,2′‐bipyridine as catalysts in the solvent N,N‐dimethylformamide. For methyl methacrylate, a kinetic plot of ln([M]₀/[M]) (where [M]₀ is the initial monomer concentration and [M] is the monomer concentration) versus time for the graft polymerization was almost linear, and the molecular weight of the graft copolymer increased with increasing conversion, this being typical for ATRP. The formation of the graft polymer was confirmed with gel permeation chromatography, ¹H‐NMR, and Fourier transform infrared spectroscopy. The glass‐transition temperature of the copolymer increased with the concentration of methyl methacrylate. The graft copolymer was hydrolyzed, and its swelling capacity was measured. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 183–189, 2005     

Synthesis of block copolymers via redox polymerization

Polymerization and copolymerization of vinyl monomers such as acrylamide, acrylonitrile, vinyl acetate, and acrylic acid with a redox system of Ce(IV) and organic reducing agents containing hydroxy groups were studied. The reducing compounds were poly(ethylene glycol)s, halogen‐containing polyols, and depolymerization products of poly(ethylene terephthalate). Copolymers of poly(ethylene glycol)s‐b‐polyacrylonitrile, poly(ethylene glycol)s‐b‐poly(acrylonitrile‐co‐vinyl acetate), poly(ethylene glycol)s‐b‐polyacrylamide, poly(ethylene glycol)s‐b‐poly(acrylamide‐co‐vinyl acetate), poly(1‐chloromethyl ethylene glycol)‐bpoly(acrylonitrile‐co‐vinyl acetate), and bis[poly(ethylene glycol terephthalate)]‐b‐poly(acrylonitrile‐co‐vinyl acetate) were produced. The yield of acrylamide polymerization and the molecular weight of the copolymer increased considerably if about 4% vinyl acetate was added into the acrylamide monomer. However, the molecular weight of the copolymer was decreased when 4% vinyl acetate was added into the acrylonitrile monomer. Physical properties such as solubility, water absorption, resistance to UV light, and viscosities of the copolymers were studied and their possible uses are discussed. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1385–1395, 1999     

Irradiation of highly oriented polyethylene fibers in the atmosphere of some vinyl monomers: Effect on compressive strength

Highly oriented polyethylene fibers have been modified by γ‐irradiation in the presence of some vinyl monomer vapors, followed with further annealing in the atmosphere of the same monomer. Two types of vinyl monomers that are known to produce polymers with different glass transition temperatures, namely methyl methacrylate and vinyl acetate, were studied for their effect on the compressive strength of the fiber. It was found that a significant improvement in compressive strength, measured by tensile recoil test, was obtained. The level of improvement was affected by heat treatment and the presence of monomer during irradiation. Modification with vinyl acetate was found to be more effective than methyl methacrylate. These facts suggest that the improvement in compressive strength was attributable to several factors, including structural relaxation, the presence of graft copolymer, and energy dissipation ability of the graft copolymer. It is speculated that lateral integrity of the fiber is one of the key factors that prevents sliding of microfibril and possibly lateral or circumferential expansion of the fiber to accommodate kink band. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 2494–2502, 2001     

Preparation of poly(vinyl alcohol)-grafted ion exchange resin and its catalytic activity. I. Photo-induced graft copolymerization of vinyl acetate on ion exchange resin

Photo-induced graft copolymerization of vinyl acetate on sulfonic acid-type ion exchange resins was investigated. In the copolymerization on isopropylated resin, graft copolymers with graft ratios (mole ratio of monomer unit of grafts to that of the resin) of up to 0.18 were obtained, although in the copolymerization on the original resin graft copolymer was not obtained. It was found that the graft ratio showed a maximum with reaction time, and the maximum graft ratio increased with conversion of the resin from the Na salt to the Fe(III) salt. Poly(vinyl alcohol)-grafted resins were obtained with saponification of the poly(vinyl acetate)-grafted resins, and their catalytic activities on the hydrolysis of amylose were investigated. The catalytic activity of the resins was found to increase with increasing graft ratio at values above 0.10. In the present experiment, however, the maximum acceleration of the reaction was up to 1.5-fold that of the original resin because of limited graft ratio.     

Synthesis of poly(vinyl acetate) containing diblock copolymer by DPE method

Diblock copolymer poly(methyl methacrylate)‐b‐poly(vinyl acetate) (PMMA‐b‐PVAc) was prepared by 1,1‐diphenylethene (DPE) method. First, free‐radical polymerization of methyl methacrylate was carried out with AIBN as initiator in the presence of DPE, giving a DPE containing PMMA precursor with controlled molecular weight. Second, vinyl acetate was polymerized in the presence of the PMMA precursor and AIBN, and PMMA‐b‐PVAc diblock copolymer with controlled molecular weight was obtained. The formation of PMMA‐b‐PVAc was confirmed by ¹H NMR spectrum. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) were used to detect the self‐assembly behavior of the diblock polymer in methanol. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis and characterization of poly(methyl methacrylate-co-2-hydroxypropyl methacrylate)-graft-polyoxyethylene

This study involved the synthesis and characterization of an amphipathic graft copolymer, poly(methyl methacrylate-co-2-hydroxypropyl methacrylate)-graft-polyoxyethylene. This amphipathic graft copolymer was synthesized utilizing a “grafting-onto” technique in which α-hydroxy-ω-methoxypolyoxyethylene was reacted with prepolymerized poly(methyl methacrylate-co-glycidyl methacrylate). Proof of copolymer formation was illustrated using water solubility, GPC, FTIR spectroscopy, and ¹³C-NMR spectroscopy. In all cases, proof of copolymer formation is demonstrated unequivocally.     

利用规整接枝共聚物作为增容剂制备耐油热塑性弹性体

通过大单体技术合成了三种现整接校共聚物；主链为聚甲基丙烯酸及支链为甲基丙烯酸甲酯的接枝共聚物（ＰＭＡＡ－ｇ－ＰＭＭＡ）可用作氨醇橡胶与聚氯乙烯的熔融共混的增容剂，而主链为聚丙烯酰胺、支链为聚苯乙烯的接校共聚物（ＰＡＭ—ｇ－ＰＳ）及主链为聚甲基丙烯酸甲酯、支链为聚苯乙烯的接枝共聚物都能作为氯化聚乙烯与聚苯乙烯共混的增容剂。用量仅占２％即可制得耐油的热塑性共混物弹性体。     

Peroxydiphosphate–metal ion–cellulose thiocarbonate redox system‐induced graft copolymerization of vinyl monomers onto cotton fabric

The grafting of methacrylic acid (MAA) and other vinyl monomers onto cotton cellulose in fabric form was investigated in an aqueous medium with a potassium peroxydiphosphate–metal ion–cellulose thiocarbonate redox initiation system. The graft copolymerization reaction was influenced by peroxydiphosphate (PP) concentration, the pH of the reaction medium, monomer concentration, the duration and temperature of polymerization, the nature of vinyl monomers, and the nature and concentration of metallic ions (activators). On the basis of a detailed investigation of these factors, the optimal conditions for the grafting of MAA onto cotton fabric with the said redox system were as follows: [Fe²⁺] = 0.1 mmol/L, [PP] = 2 mmol/L, [MAA] = 4%, pH‐2, grafting time = 2 h, grafting temperature = 70°C, and material/liquor ratio = 1 : 50. Under these optimal conditions, the graft yields of different monomers were in the following sequence: MAA ? acrylonitrile > acrylic acid > methyl acrylate > methyl methacrylate. The unmodified cellulosic fabric (the control) had no ability to be grafted with MAA with the PP–Fe²⁺ redox system. The percentage of grafting onto the thiocarbonated cellulosic fabric was more greatly enhanced in the presence of iron salts than in their absence. This held true when the lowest concentrations of these salts were used separately. A suitable mechanism for the grafting processes is suggested, in accordance with the experimental results. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 87: 1879–1889, 2003     

Syntheses of biodegradable vinyl polymers by insertion of N-benzyl-4-vinylpyridinium chloride into the main chain

Poly(methyl methacrylate), poly(vinyl acetate), polyacrylonitrile, polystyrene, and polyacrylamide were turned biodegradable by insertion of N-benzyl-4-vinylpyridinium chloride (BVP) into the main chain. For example, half-life of polyacrylonitrile that contained 3 mol% of BVP was 21 days. Half-life of polyacrylamide that contained 11 mol% of BVP was 2.4 days. Half-life of polystyrene that contained 5 mol% of BVP was expected to be 30–40 days under the conditions where the amount of polymer was very small. Oligomers of vinyl compounds are biodegradable dissimilar to high molecular weight polymers, but they are not useful as polymeric materials. However, connection of oligomers by BVP produced biodegradable polymers. Such bridged polymers are different materials from conventional vinyl polymers, and the utility may be different to some extent, but they are substantially biodegradable.     

Phase‐separation prevention and performance improvement of poly(vinyl acetate)/TEOS hybrid using modified sol‐gel process

The formation of covalent bonds between silanols in copolymer and those in silica prevents organic–inorganic phase separation. Two series of hybrid composite materials, poly(vinyl acetate‐co‐vinyl trimethoxysilane)/TEOS and poly[vinyl acetate‐co‐3‐(trimethoxysilyl)propyl methacrylate]/TEOS, were fabricated using a modified sol‐gel process. The hybrids were transparent. Two kinds of silane coupling agents, vinyl trimethoxysilane (VTS) and 3‐(trimethoxysilyl)propyl methacrylate (γ‐MPS), were used to prevent macrophase separation through formation of covalent bonds. Thermal analysis showed that γ‐MPS was more effective than VTS for the formation of covalent bonds. Enhancement of thermal stability of the hybrids was investigated by thermogravimetric analysis. Photomicrographs of scanning electron microscopy and images of atomic force microscopy indicated that inorganic silica particles were homogeneously dispersed in less than 50 nm in organic matrix. The morphological properties of hybrids were strongly dependent on the organic–inorganic composition. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 82: 2310–2318, 2001     

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     

Grafting onto wool,XVII. Graft copolymerization of methyl acrylate and ethyl acrylate by use of VO(acac)2 as initiator. Comparison of monomer reactivities

Graft copolymerization of acceptor monomers methyl acrylate and ethyl acrylate onto Himachali wool fiber has been studied in aqueous medium by using vanadium oxyacetyl acetonate as initiator at 40, 50, 60, and 70°C. Graft copolymerization was carried out for various reaction periods and nitric acid was found to catalyse the reaction. Percentage of grafting and percent efficiency have been determined as functions of concentration of nitric acid, concentration of initiator, concentration of monomer, time, and temperature. Under optimum conditions, methyl acrylate and ethyl acrylate afforded maximum grafting to the extent of 28.4 and 18.5%, respectively. Relative reactivities of methyl acrylate and ethyl acrylate towards grafting have been compared with those of methyl methacrylate, acrylic acid and vinyl acetate reported earlier from this laboratory. Different vinyl monomers showed the following reactivity order: MMA > MA > EA > AAc > VAc. Several grafting experiments were carried out in the presence of various additives which included tert-butylhydroperoxide (TBHP), dimethylsulfoxide, pyridine, and dimethylformamide. Only TBHP was found to enhance grafting to a considerable extent, other additives decrease percent grafting of both methyl acrylate and ethyl acrylate.     

Measurements of monomer partitioning in emulsion copolymerization systems

A new apparatus to measure the equilibrium solvent activity in a multiphase system containing a particulated polymer is presented. An experimental procedure to determine the monomer partitioning in typical emulsion copolymerization systems is developed; the method is devised in a way that no phase separation between water and swollen polymer particles is required in order to determine the monomer content in each phase. The analytical technique used is quantitative gas chromatography, either of the vapor or of the liquid phases. Different monomers (styrene, methyl methacrylate, and vinyl acetate) and polymeric matrices (polystyrene and methyl methacrylate–vinyl acetate copolymer) are examined both above and below saturation conditions (corresponding to intervals II and III of an emulsion polymerization process). The experimental results are compared with predictions of a literature model. © 1996 John Wiley & Sons, Inc.     

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.