Ionic graft copolymerization. VI. Graft copolymerization of β-propiolactone and N-vinylcarbazole onto trunk polymer containing carboxylic acid,sulfonic acid,and their salts

It was pointed out in previous papers that both cationic and anionic polymerization might be involved simultaneously in grafting onto trunk polymers containing ? COOH or ? SO₃Na. The graft copolymerization of β-Propiolactone (βPL)–N-vinylcarbazole (NVCZ) onto styrene-divinylbenzene copolymers containing carboxylic acid, sulfonic acid, and their salts was carried out in order to distinguish between the polymers produced by anionic and cationic mechanisms. The polymer obtained by the polymerization of βPL–NVCZ with BF₃·OEt₂, a typical cationic catalyst, consisted mainly of NVCZ units, but the polymer obtained with BuLi, a typical anionic catalyst, consisted mainly of βPL units. In the graft copolymerization of NVCZ–βPL onto trunk polymer containing ? COOH, the NVCZ contents of the branch polymer and the tolueneinsoluble fraction were estimated to be ca. 50 mole-%; therefore these polymers were produced by both cationic and anionic mechanisms. In the case of graft copolymerization onto the trunk polymer containing SO₃Na, it was found that both cationic and anionic polymerization also occurred simultaneously.     

Ionic graft copolymerization. VII. Ionic graft copolymerization of β-propiolactone onto the trunk polymers containing pyridine,amide, sulfonyl chloride,and carboxylic acid anhydride groups

The graft copolymerization of β-propiolactone (βPL) onto the various trunk polymers containing polar substituents such as pyridine, amide, sulfonyl chloride, and carboxylic acid anhydride groups was carried out. In the grafting onto the basic trunk polymer containing 4-vinylpyriding units, two kinds of grafting mechanism are supposed. In the case of rigorously dried trunk polymer, the polymerization is initiated by betaine and proceeds with higher grafting efficiency. Another is initiated by pyridinium hydroxide and proceeds with lower grafting efficiency. Another is initiated by pyridinium hydroxide and proceeds with lower grafting efficiency in the presence of some amount of water. With acidic trunk polymer containing sulfonyl chloride groups, no graft copolymer was produced. The grafting efficiency of βPL onto the amphoteric trunk polymer containing acrylamide units was found to be between those of basic and acidic trunk polymer. In addition, the grafting by means of ionic copolymerization of βPL with maleic anhydride units contained in trunk polymer proceeded with very high grafting efficiency.     

Ionic graft copolymerization. III. Graft copolymerization of β-propiolactone onto polyacrylonitrile containing diketene units

Polyacrylonitrile (PAN)–β-propiolactone (βPL) graft copolymer was synthesized by means of the ionic polymerization of βPL in the presence of polyacrylonitrile containing diketene units by using basic catalysts. A graft copolymer was produced by the copolymerization of βPL with the lactone ring in the trunk polymer. In this graft copolymerization method, the grafting efficiency was low. However, grafting efficiency increased with the mole ratio of polymeric lactone to βPL; also higher molecular weight of PβPL favored higher grafting efficiency. The reactivity ratio of polymeric lactone to βPL was estimated to be in the range of 0.1–0.3.     

Ionic graft copolymerization. II. Graft copolymerization of β-propiolactone onto acrylonitrile–sodium acrylate copolymer

Polyacrylonitrile–β-propiolactone (βPL) graft copolymer was synthesized by means of ionic polymerization, in which polymerization of βPL was initiated by polyacrylonitrile containing a small amount of some reactive groups such as ? COOK, ? COONa, ? COOLi, and ? COOH. Lower electronegativity of the countercation favored higher total conversion and higher grafting percentage. The grafting percentage increased with the reaction time and concentration of reactive groups in the trunk polymer, but grafting efficiency varied very little under these conditions. In the bulk polymerization at 60°C., grafting efficiency was about 60%, but in the solution polymerization in toluene or dioxane, grafting efficiency was higher than in bulk or nitrobenzene.     

Ionic graft copolymerization. VIII. Homopolymerization of β-propiolactone by radical catalysts in the presence of electron acceptors and application to graft copolymerization

The polymerization of β-propiolactone (βPL) induced by radiation and by radical catalysts, the influences of radical inhibitors and electron acceptors on this polymerization, and graft copolymerization were studied. It was found that βPL was polymerized by benzoyl peroxide in the presence of electron acceptors such as maleic anhydride and acrylonitrile. This polymerization method was applied to graft copolymerization. The electron donative trunk polymer containing ether groups was heated with benzoyl peroxide or was irradiated by γ-rays from Co⁶⁰ in the presence of maleic anhydride as the electron acceptor. βPL was added subsequently to form the graft copolymer.     

Ionic graft copolymerization. IV. Polymerization of β-propiolactone by acetic acid,p-toluenesulfonic acid,and their sodium salts

Acetic acid, toluenesulfonic acid, and their salts are used as four representative ionic catalysts for polymerization of β-propiolactone (βPL). They are classified as follows: sodium acetate is an anionic catalyst, acetic acid is a neutral one having more covalent character, sodium toluene sulfonate is a neutral one having more ionic character, toluenesulfonic acid is a cationic one. The neutral catalyst having more covalent nature is hardly dissociated, and therefore the rate of polymerization is quite small; however, dissociated ions consist of a higher neucleophilic anion and a higher electrophilic cation. On the contrary, the neutral catalyst having an ionic bond dissociates more easily, but the formed ions consist of the less reactive anion and cation. Therefore, it is of interest whether β-propiolactone is polymerized by a cationic mechanism or an anionic mechanism by these catalysts. The mechanisms of polymerizations of βPL by these neutral catalysts were studied on the basis of the different behaviors of polymerizations by the four catalysts described above. In the cationic polymerization by toluenesulfonic acid, the rate of polymerization was high, but the conversion reaches a low, limited value. In the anionic polymerization by sodium acetate, the rate of polymerization was high and the degree of polymerization of polymer was the highest. Acetic acid has the lowest catalyst activity and the degree of polymerization is also very small. It was found that the polymerization by sodium p-toluenesulfonate was accelerated in the presence of acrylic acid produced from βPL by hydrogen-transfer reaction.     

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.     

Ionic graft copolymerization. I. Homopolymerization of β-propiolactone by sodium acetate catalyst

The polymerization of β-propiolactone (βPL) by sodium acetate catalyst has been investigated. The polymerization behavior with monomer purified with calcium chloride was found to be a little different from that previously reported for this monomer. That is, poly-β-propiolactone (PβPL) obtained from βPL dried with CaCl₂ has a higher degree of polymerization than that obtained from conventionally treated βPL, and its infrared spectrum shows type II configuration, which differs from that reported in previous papers. Some chain transfer reaction is observed even for the polymerization of the CaCl₂–dried βPL; however, this is less important in toluene. The electronegativity of the anion or cation in catalyst greatly influences the rate of polymerization.     

Surface grafting of polymer onto carbon thin film

The surface grafting of polymers onto carbon thin film deposited on a glass plate was achieved by two methods: the graft polymerization initiated by initiating groups introduced onto the surface; and the trapping of polymer radicals by surface aromatic rings of the thin film. It was found that the radical and cationic graft polymerization of vinyl monomers are initiated by azo and acylium perchlorate groups introduced onto the surface, respectively, and the corresponding polymers are grafted onto the surface: the surface grafting of polymers were confirmed by the contact angle of the surface with water. In addition, the anionic ring-opening alternating copolymerization of epoxides with cyclic acid anhydrides was found to be initiated by potassium carboxylate groups on the carbon thin film to give the corresponding polyester-grafted carbon thin film. On the other hand, polymer radicals formed by the decomposition of azo polymer, such as poly(polydimethylsiloxane-azobiscyanopentanoate) and poly(polyoxyethylene-azobiscyanopentanoate), were successfully trapped by the surface aromatic rings of carbon thin film and polydimethylsiloxane and polyoxyethylene were grafted onto the surface. © 1995 John Wiley & Sons, Inc.     

Grafting of polyesters onto carbon black. III. Polymerization of β-propiolactone initiated by quaternary ammonium carboxylate groups on the surface of carbon black

By use of carbon black containing quaternary ammonium carboxylate (COO^?N⁺R₄) groups as catalyst, the anionic ring opening polymerization of β-propiolactone (PL) was carried out at 50°C. Although carbon black itself was unable to initiate the polymerization of PL, carbon black containing COO^?N⁺R₄ groups, which was prepared by the reaction of carboxyl groups with corresponding quaternary ammonium hydroxide, was found to be able to initiate the polymerization. The carbon black obtained from the polymerization gave a stable colloidal dispersion in an organic solvent, and it was confirmed that the polyester formed was effectively grafted onto the surface. In addition, the effect of quaternary ammonium countercation on the polymerization was investigated.     

Polymerization and graft copolymerization of styrene initiated by ceric ion in acetonitrile/water solution

The polymerization of styrene initiated by a ceric ion/pinacol system and the graft copolymerization of styrene onto microcrystalline cellulose initiated by ceric ion were studied in the mixed solution composed of acetonitrile and water. Although the graft copolymer of polystyrene onto microcrystalline cellulose was not obtained in the acetonitrile solution, addition of water initiated the polymerization, and the grafting ratio was increased with increasing the water added. The rate of polymerization of styrene in the ceric ion/pinacol system increased similarly with increasing the water content in the solution. Acetonitrile is miscible with water, but the solution was separated to two phases by adding styrene into the solution containing above 20% of water; the monomer was dissolved in both acetonitrile and water phases. The polymer was undissolved in this mixed solution. The effects of water on the polymerization in the mixed solvent system are discussed from the standpoint of reaction mechanism.     

Graft copolymerization of methyl methacrylate onto wool using thallium (III) ions as initiator

The graft copolymerization of methyl methacrylate onto wool initiated by thallium (III) perchloric was investigated in aqueous perchloric acid medium. The rate of grafting was evaluated varying the concentrations of the monomer, initiator, acid, and temperature. The rate of grafting was found to increase with the increase of the monomer and the initiator concentration. The graft yield was found to decrease upon increasing the acid concentration. Increase of temperature was accompanied with the increase of the graft yield. From the Arrhenius plot the overall activation energy was calculated to be 4.7 kcal/mol. The effect of inhibitors, various solvents, cationic and anionic surfactants, and different inorganic salts on the graft yield was studied. The grafting was considerably influenced by chemical modification of wool prior to grafting. A suitable kinetic scheme has been proposed, and a rate equation has been derived.     

黄原胶与丙烯酰胺接枝共聚反应的研究

以过硫酸铵为引发剂,在氮气保护下,研究了黄原胶与丙烯酰胺的接枝共聚反应。考察了单体浓度、引发剂浓度、反应温度和反应时间等因素对接枝率及接枝效率的影响,探讨了过硫酸铵引发黄原胶接枝丙烯酰胺共聚反应的基本规律。采用红外光谱、X射线粉末衍射对接枝共聚物的结构进行研究,用热重分析法表征了产物的热性能,并初步探讨了接枝机理。结果表明,过硫酸铵能有效地引发黄原胶与丙烯酰胺的接枝共聚反应,并且接枝率和接枝效率随单体浓度、引发剂浓度、反应温度的变化出现极大值,随反应时间的延长不断上升,直至基本不变。     

Graft copolymerization of methyl methacrylate onto polypropylene oxidized with ozone

After the reaction of polypropylene by ozone oxidation, methyl methacrylate was graftcopolymerized onto the polypropylene. The active species determined by ESR spectroscopy as a peroxyl radical was converted to hydroperoxide, and the hydroperoxide was broken by heating, giving alkoxyl and hydroxyl radicals, the former of which initiated graft copolymerization. The effect of the ozone-oxidation time and polymerization time on the graft copolymerization was investigated. At the constant polymerization time, the total conversion and the degree of the grafting increased with the ozone-oxidation time, while the graft efficiency decreased. On the other hand, at the constant oxidation time, the total conversion and the degree of grafting increased with the polymerization time, while the graft efficiency decreased. These results were compared with a polyethylene case. The mechanism of the ozone oxidation and the initiation of the graft copolymerization were also discussed.     

Radiation-Induced graft copolymerization,I. Graft copolymerization of methyl methacrylate onto nylon-6

The radiation-induced graft copolymerization of methyl methacrylate onto nylon fibers was investigated at room temperature. The homopolymer was separated by soxhlet extraction. The graft yield increases with increase of dose rate from 0.1768 to 0.7072 Mrad. The percentage of grafting increase with increasing monomer concentration. Addition of copper sulphate and a non-ionic surfactant, sodium lauryl sulphate, supresses the formation of homopolymer. The value of G_b, the number of branches per 100 eV of energy absorbed in the substrate polymer, and the value of α, the fraction of substrate polymer grafted, have been computed. A kinetic scheme has been suggested.     

Studies on graft copolymerization of acrylate monomers onto casein

Poly(butyl acrylate) has been graft copolymerized onto casein using potassium peroxydisulfate–ascorbic acid as the initiating system. The proof of grafting has been obtained by ninhydrin test and IR studies. The effects of synthetic variables in the graft copolymerization have been discussed in the light of percent grafting, grafting efficiency, and the rates of polymerization.     

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     

Studies on graft copolymerization of acrylonitrile onto jute fiber with permanganate ion initiation system in presence of air

The graft copolymerization of acrylonitrile with jute using potassium permanganate as the initiator has been studied in the presence of air. To establish reaction conditions for the graft copolymerization of acrylonitrile (AN) onto jute, the effect of different variables such as the residual lignin content of bleached jute (after bleaching with sodium chlorite), initiator concentration, monomer concentration, time of polymerization, reaction temperature, and amount of bleached jute fiber have been studied. As evidence of polymer grafting, some instrumental analyses such as scanning electron microscopy, infrared, and thermogravimetry have been carried out. The extent of grafting of acrylonitrile depends on how much lignin is present on the jute fiber. Percent grafting and grafting efficiency have also been studied. © 1995 John Wiley & Sons, Inc.     

Modification of Tefzel film through graft copolymerization

The graft copolymerization of styrene (st) and methacrylonitrile (MAN) onto Tefzel film in aqueous media by the preirradiation method has been studied. In order to follow the effect of preswelling of the backbone polymer, grafting was attempted onto preirradiated Tefzel film and monomer preswollen, preirradiated Tefzel film. Optimum conditions pertaining to maximum percentage of grafting of st and MAN have been evaluated. Grafting onto preswollen, preirradiated Tefzel film displayed better results. The effect of different alcohols of increasing chain length on the percentage of grafting of st and MAN was also studied. Graft copolymerization of st showed an increase, while grafting with MAN exhibited a decrease, in the percentage of grafting in the presence of alcohols as compared to that obtained in the aqueous medium. Characterization of the graft copolymers was made by IR and thermogravimetric studies. Tefzel‐graft‐polystyrene showed improved thermal stability while the MAN grafted onto preswollen, preirradiated Tefzel film produced graft copolymer with poor thermal stability. Copyright © 2004 Society of Chemical Industry     

Graft copolymerization of styrene onto ethylene-vinyl p-nitrobenzoate copolymer by chain transfer reaction

The effect of steric hindrance on the attack of growing polymer radicals to the reaction sites on a trunk polymer was examined in the graft copolymerization of styrene onto a trunk polymer with pendant aromatic nitro groups by chain transfer reaction of growing polymer radicals to the pendant nitro groups. The nitro groups on ethylene-vinyl p-nitro benzoate copolymer (EVNB) are more effectively utilized in the graft copolymerization than those on the vinyl p-nitro benzoate homopolymer (PVNB) previously used as a trunk polymer, because the nitro groups are distributed less frequently on the trunk polymer in the former than in the latter. This was also confirmed by the higher chain transfer constant of growing polystyrene radicals to EVNB compared to that of PVNB.