Kinetics of Aqueous Polymerization of Acrylamide Initiated by Ceric Ammonium Sulfate/2-Mercaptoethanol Redox System

Polymerization of acrylamide monomer, initiated by the redox system involving acidified ceric ammonium sulfate and 2-mercaptoethanol (2-ME) was carried out in an aqueous medium at 25° C. White, rigid polyacrylamide, isolated under controlled experimental conditions, showed a molecular weight of 1.5 × 10⁴ from viscosity measurements. The rate of monomer (M) conversion to polymer was found to be proportional to [M]^1.5, [2-ME]^0.5, and [Ce(IV)]^0.4. Further, the rate of disappearance of ceric ion was observed to be directly proportional to [2-ME] and independent of [M] in the range of 0.16–0.48 mole/liter. The explanation of the above proportionalities is given in terms of a proposed reaction mechanism. Values of the usual rate constants, k_r, k₀/k_t and k_t./k_p ^½ have been computed.     

偶氮基团引发PMMA在纳米TiO2表面接枝聚合研究

采用表面接枝反应的方法,在纳米TiO2上接枝偶联剂KH-560,进而通过酯化反应引入偶氮基团引发甲基丙烯酸甲酯发生自由基聚合反应,并通过IR、SEM、TEM、DSC和TG等测试方法研究了反应条件对复合粒子结构和性能的影响.结果表明,反应约60 min时,TiO2表面的接枝率达42.9%;当搅拌速率为1.0×104 r/min时,TiO2均匀分散在PMMA基体中;TiO2粒子的加入使得PMMA的热稳定性有了明显提高.     

Graft Polymerization of Vinyl Monomers Onto Carbon Black by Use of the Redox System Consisting of Ceric Ions and Carbon Black Carrying Alcoholic Hydroxyl Groups

The radical graft polymerization of vinyl monomers onto carbon black initiated by a redox system consisting of ceric ion and carbon black having alcoholic hydroxyl groups was investigated. The introduction of alcoholic hydroxyl groups onto the carbon black surface was achieved by the reaction of carbon black with alcoholic hydroxyl radicals, formed by the reaction of alcohol with benzoyl peroxide. The rate of the polymerization of acrylamide (AAm) initiated by the redox system was found to increase in the following order of hydroxyl groups: 1-hydroxyoctyl < 1-hydroxypropyl < 1-hydroxyethyl < hydroxymethyl < 1-hydroxy-1-methylethyl. In the redox polymerization, poly-AAm was effectively grafted onto carbon black by propagation of the polymer from the radical formed by the reaction of ceric ions with the alcoholic hydroxy groups. The percentage of grafting increased with increasing conversion. By use of this redox system, poly(acrylic acid), polyacrylonitrile, and poly(N-vinyl-2-pyrrolidone) could be grafted onto carbon black, but poly(methyl methacrylate) and polystyrene could not be so grafted. The graft polymerization of AAm by use of a redox system consisting of ceric ion and PVA-grafted carbon black was also investigated.     

Grafting of Polymers onto Activated Carbon Surface: Graft Polymerization of Vinyl Monomers Initiated by Azo Groups That Were Introduced onto the Surface

Abstract

We examined the grafting of polymers onto an activated carbon powder surface by polymerization that was initiated by azo groups that were introduced onto the surface as well as the effects of grafted polymers on the adsorption of acetic acid. The introduction of azo groups onto the surface was achieved by the following methods: (1) a reaction of 4,4′-azobis(4-cyano-pentanoic acid) (ACPA) with surface isocyanate groups that were introduced beforehand by treatment with tolylene 2,4-diisocyanate (AC-Azo 1) and (2) the direct condensation of ACPA with surface phenolic hydroxyl groups by using N,N'-dicyclohexylcarbodiimide (AC-Azo 2). The radical polymerizations of styrene, methyl methacrylate, N,N-diethylacrylamide (DEAM), and N-isopropylacrylamide (NIPAM), were successfully initiated by the azo groups on the surface and the corresponding polymers were grafted onto the surface. There was a significant decrease in the adsorption of the acetic acid of the activated carbons when polymers were grafted onto them, particularly in regards to the grafting of hydrophobic polymers. On the other hand, a decrease in the adsorbability of the polyDEAM-grafted and polyNIPAM-grafted activated carbon was barely observed. In addition, polyDEAM-grafted and polyNIPAM-grafted activated carbons showed temperature-dependent adsorption of acetic acid: the adsorbability of these activated carbon decreased above lower critical solution temperature of these polymers, which is about 32°C.     

Grafting of Methyl Acrylate onto Cellulose by Ceric Ion

Abstract

Methyl acrylate was grafted onto dissolving pulp by ceric ion in aqueous sulfuric acid under oxygen-free argon. At a low Ce(IV) concentration (up to 1 mmol/L), the rate of polymerization (R_p ) is proportional to [Ce]^0.5 [MA]¹ [cellulose]¹. At higher concentrations of cericion (1–20 mmol/L), R_p is proportional to [Ce]⁰ [M] ^1.5 [cellulose]¹. The mechanism of grafting is consistent with a kinetic scheme involving initiation by primary radicals and termination by growing polymer radicals. Above 20 mmol/L of ceric salt, the data are consistent with the linear termination mode.     

Polymerization of Methacrylamide Initiated by Ceric Ion-Citric Acid Redox System

Homogeneous polymerization of methacrylamide initiated by the ceric ammonium sulfate-citric acid (CA) redox pair has been investigated and reported at 35 ± 0.2°C under nitrogen atmosphere. The initiation was caused by the free radical generated by the decomposition of the complex formed between ceric ion and citric acid. The rate of monomer disappearance was found to be proportional to [CA]^0.4, [Ce^0.4+]^0.65, and [Monomer]¹ The rate of ceric ion disappearance was directly proportional to the ceric ion concentration but independent of the monomer concentration. The initial rate was independent of [H₂SO₄]. The activation energy of the system was found to be 21.4 kJ/mol.     

辣根过氧化物酶酶促体系引发丙烯酰胺聚合的研究

对辣根过氧化物酶(HRP)、H2O2和乙酰丙酮(ACAC)组成的三元醇促体系引发的丙烯酰胺(AAM)聚合进行了研究。在膨胀计中考察了反应温度和HRP、ACAC、H2O2及AAM初始浓度对酶促体系引发AAM聚合动力学行为的影响,确定了适宜的反应条件。用FTIR和GPC对聚合产物进行表征,得到的聚丙烯酰胺的数均分子量为10^5-10^6,分子量分布指教DI为2-3。     

Cationic Grafting of Vinyl Polymers onto a Carbon Whisker,Initiated by Acylium Perchlorate Groups Introduced onto the Surface

Abstract

The cationic graft polymerization of vinyl monomers onto a carbon whisker, vapor-grown carbon fiber, initiated by acylium perchlorate groups introduced onto the surface, was investigated. The introduction of acylium perchlorate groups onto a carbon whisker was achieved by the treatment of a carbon whisker having acyl chloride groups, which were introduced by the reaction of surface carboxyl groups with thionyl chloride, with silver perchlorate in nitrobenzene. It was found that the cationic polymerization of vinyl monomers, such as styrene, indene, N-vinyl-2-pyrrolidone, and n-butyl vinyl ether, is initiated by acylium perchlorate groups on a carbon whisker. In the polymerization, the corresponding vinyl polymers were grafted onto a carbon-whisker surface based on the propagation of polymer from the surface: the percentage of grafting of polystyrene and polyindene reached 42.5 and 100.3%, respectively. The percentage of polystyrene grafting decreased with increasing polymerization temperature because of preferential chain transfer reactions at higher temperatures. Polymer-grafted carbon whisker gave a stable colloidal dispersion in a good solvent for grafted polymer.     

胶囊固定化辣根过氧化物酶酶促体系引发丙烯酰胺聚合研究

研究了以海藻酸钠／壳聚糖／海藻酸钠为囊壁材料的胶囊固定化辣根过氧化物酶的制备及其影响因素,并将肢囊固定化辣根过氧化物酶／乙酰丙酮／H2O2酶促体系用于引发丙稀酰胺的聚合。结果表明,作为囊壁材料之一的壳聚糖的平均分子量以1万左右为宜,以柠檬三酸钠溶液为溶芯荆的溶芯时间控制在2～4min时,固定化率可达60％,相对于游离酶,其相对活力约为60％。胶囊固定化辣根过氧化物酶／乙酰丙酮／H2O2酶促体系可引发丙稀酰胺的聚合。     

Polymerization of Acrylamide Initiated by Hydroxy Terminated Polybutadiene-ceric Ammonium Nitrate Redox System

Amphiphilic copolymer of acrylamide (AAm) and butadiene was synthesized by radical initiation using the hydroxy terminated polybutadiene (HTPB) and ceric ammonium nitrate (CAN) macroredox initiator in heterogenous medium in the presence of nitric acid at 35°C in air. The resulting product was characterized by IR, NMR, viscosity and swelling measurements. Imidization of some AAm units was inferred from NMR spectroscopy and swelling measurement. The product adsorbed Ni(II) and Fe(II) ions from aqueous solution and selectively released Ni(II) only. The release pattern for hydrophilic dye was similar to the usual fractional release behavior of drug release observed for hydrogel systems.     

3-甲基丙烯酰胺基-9-乙基咔唑-过硫酸钾氧化还原体系引发丙烯酰胺聚合

合成了可聚合芳香叔胺-3-甲基丙烯酰胺基-9-乙基咔唑,并与过硫酸钾组成氧化还原引发体系引发丙烯酰胺水溶液聚合,测定了聚合反应动力学,得到了超高分子量的聚丙烯酰胺.     

Grafting of 4-Vinyl Pyridine onto Nylon-6 Initiated by Redox System

The graft copolymerization of 4‐vinyl pyridine (4VP) onto nylon‐6 (PA6) was studied by using potassium diperiodatonickelate(IV) (DPN)‐PA6 redox system in alkaline medium. The structures of graft copolymers were confirmed by Fourier transfer infrared spectroscopy (FTIR) and X‐ray diffraction. The properties of graft copolymers were investigated by thermogravimetric analysis (TGA). A mechanism was proposed to explain the generation of radicals and the initiation. The effects of reaction variables, such as the initiator concentration, the ratio of 4VP to PA6, pH as well as reaction temperature and time were investigated. Graft copolymers with high grafting efficiency (>95%) were obtained, which indicated that DPN‐PA6 redox system is an efficient initiator for this graft copolymerization. The quaternized PA6‐g‐P4VP (QPAVP) was proved to be an excellent adsorbent to heavy metal ions.     

3—甲基丙烯酰胺基—9—乙基咔唑—过硫酸钾氧化还原体系引发 …

合成了可聚合芳香叔胺－３－甲基丙烯酰胺基－９－乙基咔唑,并与过硫酸钾组成氧化还原引发体系引发丙烯酰胺水溶液聚合,测定了聚合反应动力学,得到了超高分子量的聚丙烯酰胺。     

Vinyl Polymerization. 287. Polymerization of Methyl Methacrylate Initiated by the Polyacrylonitrile-Water-Cupric Ion System

Abstract

Methyl methacrylate was found to be polymerized by the system polyacrylonitrile-water-cupric ion without any added initiator. Addition of carbon tetrachloride to this system greatly increased the polymerization rate. Acrylonitrile and styrene did not polymerize in this system. The kinetic behavior of polymerization was the same as the system consisting'of cellulose or nylon instead of polyacrylonitrile. When the flaky polyacrylo-nitrile was swelled or dissolved by the solvent DMF, the conversion and the degree of polymerization of the poly-methyl methacrylate formed decreased markedly. Commercial acrylic fiber also initiated polymerization but the activity was lower than with flaky polyacrylonitrile, even after steam treatment, because of the poor permeability of monomer into the fiber.     

铈离子氧化还原引发体系与铈离子引发接枝或嵌段共聚合研究的新进展

本文介绍Ce⁴⁺/酰胺引发体系;Ce⁴⁺/聚酰胺、带酰苯胺侧基的聚合物引发接枝共聚合;Ce⁴⁺/氨基甲酸酯引发体系;Ce⁴⁺/聚醚氨酯引发接枝共聚合;Ce⁴⁺/羰基化合物引发体系;Ce⁴⁺引发嵌段共聚合6个方面的研究新进展.     

Aqueous Polymerization of Acrylamide Initiated by Glycolic Acid/Ce4+ Redox System

The aqueous polymerization of acrylamide initiated by the glycolic acid/Ce⁴⁺ redox system was studied in sulfuric acid medium at 35 ± 0.2°C under a nitrogen atmosphere. The initiation was carried out by the free radical generated in the decomposition of the complex formed between the oxidant and the reductant. The monomer disappearance was found to be proportional to [GA]^0,89[Ce⁴⁺]^0.57[M]^1.0, and the rate of ceric ion disappearance was found to be directly proportional to [Ce⁴⁺] and [GA] but independent of [M]. The activation energy of the system was found to be 7.21 kcal/deg/mol. The molecular weight of polyacrylamide increased with increasing [monomer] and decreased with increasing [catalyst]. The effect of pH was also studied in the pH range 2.22 to 1.44.     

Initiation Mechanism of Polymerization of Acryl－amide by Ceric Ion／2－Benzoyl Acetanilide System

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Radical Graft Polymerization of Vinyl Monomers Initiated by A20 Groups Introduced Onto a Carbon Black Surface: Effect of azo Groups on Graft Polymerization

The radical graft polymerization of vinyl monomers from carbon black initiated by azo groups introduced onto the surface was investigated. The introduction of azo groups onto carbon black surface was achieved by three methods: the reaction of 2,2′-azobis[2-(2-imidazolin-2-yl)propane] (AIP) with (1) epoxide groups, which were introduced by the reaction of carbon black with chlorometh-yloxirane; (2) acyl chloride groups, which were introduced by the reaction of carboxyl groups on the surface with thionyl chloride; and (3) 3-chloroformyl-1-cyano-1-methylpropyl groups, which were introduced by the reaction of carbon black with 4,4′-azobis(4-cyanovaleric acid) and then thionyl chloride. The amount of azo groups introduced onto the surface by the above methods was determined to be 0.07-0.19 mmol/g. The graft polymerization of methyl methacrylate was found to be initiated by azo groups introduced onto the carbon black surface. During the polymerization, poly(methyl methacrylate) was effectively grafted onto carbon black through propagation of the polymer from the radical produced on the surface by the decomposition of the azo groups. The percentage of grafting using carbon black having azo groups introduced by method 1 increased to 40%. It was also found that the graft polymerization of several vinyl monomers such as styrene, acrylonitrile, and acrylic acid was initiated by the azo groups introduced onto the surface and the corresponding polymer was effectively grafted onto the surface. Furthermore, the effect of the amount of carbon black having azo groups on the graft polymerization was investigated.     

Vinyl Polymerization Initiated by the Methylated Cyclodextrin/Metal Ion System in Water

The polymerization of the vinyl monomers methyl methacrylate (MMA), benzyl methacrylate, and styrene, has been carried out using methylated cyclodextrins, for example, heptakis(2,6,0-dimethyl)-β-cyclodextrin, and heptakis (2,3,6-0-trimethyl)-β-cyclodextrin. These methylated cyclodextrins were found to initiate polymerization of the vinyl monomers in combination with water and a small amount of Cu(II) ion, in analogy with β-cyclo-dextrin (β-CD). Generally, the initiating ability of the methylated cyclodextrins/Cu(II) ion system for the polymerization of MMA was larger than that of the β-CD/Cu(II) ion system. Moreover, the introduction of a phosphate group into a methylated cyclodextrin molecule was found to increase the initiating ability for the polymerization of MMA.     

Polymerization of Acrylamide Initiated by the Redox System Potassium Persulfate/Lactic Acid,Catalyzed by Silver Ions

The aqueous polymerization of acrylamide initiated by the potassium persulfate/lactic acid system catalyzed by Ag⁺ ions has been studied iodometrically over the temperature range from 35 to 50 ± 0.2°C. The rate of polymerization is governed by the expression R_p ∞ [M]^0.8[K₂S₂O₈]^1.0[Ag]^1.0 The deviation from normal kinetics has been studied. A tentative mechanism of initiation is suggested. The overall energy of activation is 5.52 kcal/mol.