Vinyl Polymerization by Metal Complexes. XXXI. Initiation by Chitosan-Copper(II) Complex

The polymerization of methyl methacrylate and acrylonitrile can be initiated by the chitosan-copper(II) complex and its monomeric form, glucosamine-copper(II) complex, in the presence of carbon tetrachloride. The chitosan complex system was found to be more active for initiating the polymerization of methyl methacrylate than acrylonitrile at neutral pH. On the other hand, the glucosamine complex system showed no activity at neutral pH region, but had high activity at higher pH, because of the reducing endgroup of the glucosamine. Formation of the copper(II) complexes was studied by pH titration and visible spectroscopy. The relationship between complex formation and the activity for initiating the polymerization is discussed.     

Vinyl Polymerization by Metal Complexes. XV. Polymerization of Acrylonitrile Initiated by Imidazole-Copper(II) Complex

The polymerization of acrylonitrile initiated with the imidazole-copper (II) complexes was studied in dimethylsulfoxide solution. The ability of the complexes to initiate polymerization seems to depend on their anion. 2-Substituted imidazole-copper (II) complexes of the type, CuL₄X₂ (L = imidazole as ligand and X = anion), were also found to initiate vinyl polymerization. From the data of electronic spectra in dimethylsulfoxide solution, the initiation mechanism is discussed in terms of the formation of the active species by the interaction of the complex with monomer molecules.     

Vinyl Polymerization. 401. Polymerization of Vinyl Monomer Initiated with Poly-2-hydroxyethylmethacrylate

The polymerization of vinyl monomer initiated with poly-2-hydroxyethylmethacrylate (PHEMA) in water was carried out at 85°C. Cu(II) ion was not necessary for this polymerization. Methacrylate monomers were polymerized, while styrene and acrylonitrile were not. The polymerization was found to proceed through a radical mechanism in the interior of PHEMA which was swelled in water. The grafting efficiency of MMA polymer obtained was about 90%. The overall activation energy was estimated to be 32.9 kJ/mol.     

Vinyl Polymerization. 377. Polymerization of Methyl Methacrylate by the System of Lysozyme,Copper(II) Ion,and Water

The polymerization of methyl methacrylate (MMA) initiated by the system lysozyme, copper(II) chloride, and water was carried out. The effect of the amount of each component on the conversion of MMA was studied. The polymerization proceeded through a radical mechanism. Urea, known to be a denaturing agent for protein, was able to promote the polymerization. On addition of urea, it was found that the following three reactions took place: (1) promotion of the polymerization of MMA with lysozyme, Cu(II) ion, and water by the unfolding of the third structure of lysozyme, (2) polymerization initiated by urea and Cu(II) ion, (3) polymerization initiated by the S-S bonds of lysozyme and urea.     

Vinyl Polymerization by Metal Complexes. XXXIII. Polymerization of Acrylonitrile Initiated by Triazole-Copper(II) Complex in Dimethylsulfoxide Solution

Polymerization of acrylonitrile initiated by triazole-copper(II) complexes was studied in dimethylsulfoxide solution. It was found that the polymerization proceeds by a free radical mechanism; however, the complexes can hardly homopolymerize methyl methacrylate and styrene. Ability of the complexes to initiate polymerization seems to depend on the substituents of triazole, the sort of solvents, and the counterions of copper(n) salts. From the data of visible spectroscopy and the spin trapping, the initiation mechanism was discussed in terms of reduction of copper(II) followed by forming active species.     

Studies on the Self-condensing Vinyl Polymerization of a Novel Maleimide Inimer

The self-condensing vinyl polymerization(SCVP) of a novel maleimide inimer(initiator-monomer) 1, N-(4-α-bromobutyryloxy phenyl) maleimide with the complex of CuBr/Bipy (2, 2‘-bipyridine) as the catalyst was studied. GPC was used to determine the molecular weight and the results show that the molecular weight increases exponentially with polymerization time during the first hour, and then the rate of increase molecular weight slows down. The molecular weight also increases with increasing dosage of the catalyst. The coincidence of the molecular weights determined by ^1H NMR and GPC proves that the polymer obtained from the SCVP of inimer 1 has a linear structure, whichis further verified by ^13C NMR spectrum. A hyperbranched polymer was obtained by the copolymerization of inimer 1 and styrene.     

非手性席夫碱-异丙氧基铝引发外消旋丙交酯的立构选择性聚合

摘要以非手性的席夫碱-异丙氧基铝(Ⅱ)引发外消旋丙交酯(rac-LA)的立构选择性聚合. 其聚合动力学研究结果表明, 聚合反应对于单体符合一级反应动力学. 所得聚合物的数均分子量与单体转化率成正比, 并且分子量分布很窄, 表明该聚合反应具有良好的可控性. 此外所得的聚外消旋乳酸是tm为179 ℃的结晶性聚合物. 13C NMR和同核去偶1H NMR谱表明, 所得的聚乳酸是一种立构嵌段聚合物, 平均嵌段长度为11个乳酸单元.     

Vinyl Polymerization. 418. Polymerization of Vinyl Monomer Initiated by Betaine-Type Polymers in Aqueous Solution

Abstract

Three kinds of betaine-type polymers, which are macromolecular amphoteric electrolytes, were found to be able to polymerize vinyl monomers in aqueous solution through a radical mechanism without any further initiator. Betain-type polymers form hydrophobic areas (HA) in water. Vinyl polymerization commenced in the HA. The effect of the pH of the aqueous solution on polymerization was investigated.     

Cationic Polymerization Behavior of Some Vinyl Ketone Cyclodimers

Cationic polymerizations of 2,3-dihydropyran derivatives, methyl isopropenyl ketone cyclodimer (MIPKD), chloromethyl vinyl ketone cyclodimer (CMVKD), and methyl isopropenyl ketone-chloromethyl vinyl ketone cyclocodimer, D(MIPK-CMVK), were investigated in the presence of various Lewis acids at 0°C. These monomers were found to undergo cationic polymerization to give low molecular weight polymer which consisted mainly of a vinylene structure. However, the ring-opening polymerization was found to occur to a minor extent in cationic polymerizations of MIPKD and D(MIPK-CMVK) cyclodimer.     

Vinyl Polymerization. 436. Effect of Magnetic Field on Uncatalyzed Polymerization

The radical polymerization of vinyl monomers initiated with several kinds of hydrophilic macromolecule was carried out in a magnetic field. The magnetic field promoted the polymerization; the conversion of monomers and the molecular weight of the polymers obtained increased with increasing field strength in the range of 0–0.1 T. The dependence of the composition and tacticity of the mother polymer on the magnitude of the magnetic field was studied. Using graft or block copolymers, which consisted of hard and soft segments, the effect of a magnetic field was further investigated. The degree of hardness and tightness of the hydrophobic areas (reaction areas) formed by the mother polymer in the aqueous solution was found to affect the magnetic field effect on the uncatalyzed polymerization. The overall activation energy obtained in the magnetic field was almost equal to that obtained without a magnetic field.     

Vinyl Polymerization. 274. Polymerization of Acrylonitrile Initiated by the System Tetramethyl Tetrazene and Co(II) Chloride

Abstract

The binary system of tetramethyl tetrazene (TMT) and Co(II) chloride was used as initiator of acrylonitrile (AN) in dimethylformamide. The initial rate of polymerization (Rp) was found to be expressed by Rp = k[TMT]^0.62[Co(II) chloride]^0.57 [AN]^2.00

The polymerization was confirmed to proceed via a radical mechanism. The over-all activation energy for the polymerization was estimated as 15.1 kcal/mole. On the basis of these results and the product analysis of the reaction between the catalyst components in the absence of monomer, the initiation mechanism of the polymerization is discussed.     

Vinyl Polymerization by Carbon Black. II. Modification of Carbon Black and Its Use in the Polymerization of N-Vinylcarbazole

Modification of carbon black N220, ISAF-HM, by aprotonic and protonic acids uniquely improves its catalytic activity in relation to the polymerization of N-vinylcarbazole. The polymerization is first order in monomer and directly proportional to the weight of the catalyst. However, the molecular weights of the polymer do not depend significantly on the nature of the modification. Heat treatment of the catalysts at 500°C reduces the yield of polymer drastically. The activation energy of the polymerization by unmodified carbon black is 83 kJ/mol as compared to 71 kJ/mol for the modified catalyst. Modification by dialkylzinc (0.1 to 0.4 M) produces stereoregularity as indicated by the MEK insolubility of the polymer.     

通过自缩合乙烯基氧阴离子聚合制备超支化聚甲基丙烯酸羟丙酯

由甲基丙烯酸羟丙酯通过自缩合乙烯基氧阴离子聚合(self-condensing vinyl oxyanionic polymerization)制备了端羟基的超支化聚甲基丙烯酸酯. 以氢化钾(KH)和冠醚的复合物为引发剂时, 可以得到高分子量的聚合物. 用¹H NMR和¹³C NMR谱图证实了聚合物的超支化结构. 由于在聚合过程中存在质子转移反应, 引发剂与单体的摩尔比会影响所得聚合物的结构. 超支化聚合物的玻璃化转变温度在58.1～81.4 ℃之间, 且随着引发剂与单体的比例的减小而降低. 当引发剂与单体等摩尔比时, 所得聚合物的支化度为0.49.     

Studies in Vinyl Polymerization. Reinitiation by Allyl Chloride Transfer Radicals in the Polymerization of Vinyl Acetate

The kinetics of vinyl acetate polymerization in the presence of allyl chloride were studied by a dilatometric method. The retardation of the rate of polymerization was explained in terms of degradative chain transfer to allyl chloride. Analysis of the polymerization rate data indicates that a relatively large proportion of the allyl chloride transfer radicals is reactive toward initiation.     

Vinyl Polymerization. 254.∗ Polymerization of Methyl Methacrylate by the System Cellulose-Water-Carbon Tetrachloride

Radical polymerization of methyl methacrylate initiated by the system cellulose-water-carbon tetrachloride was kinetically studied. Results obtained are: 1) The amounts of water, carbon tetrachloride, and cellulose affected the conversion. Michaelis-Menten's equation was applied to the relationship between the rate of polymerization and the amount of MMA. 2) Other methacrylates and acrylates were also polymerized by this system. 3) When methanol or ethanol was used instead of water, some weak polymerization activity was observed. 4) Initiating ability depended on the kind of cellulose used. 5) The activity of cellulose was not changed by washing with boiling water or by solvent extraction. 6) Polymerization was inhibited by the presence of air. 7) Heating in the presence of water and carbon tetrachloride markedly decreased the activity of the cellulose.     

Vinyl Polymerization by Metal Complexes. VII

Abstract

The photopolymerization of vinyl monomers by metal salt-saccharide system was investigated in various solvents. The rate of polymerization in the presence of a iron(III) salt in aqueous media was remarkably accelerated by the addition of saccharides. The acceleration caused by a series of saccharides was found to be in the following order: glucose > fructose > lactose maltose. α-Methyl-d-glucoside and sucrose exhibited very little effect. The overall activation energy for the photopolymerization of acrylonitrile in the presence of glucose was found to be 2.7 kcal/mole, about half of the value obtained in the absence of glucose.     

The Formation of Terminal Double Bonds in Vinyl Chloride Polymerization

The determination of double bonds in PVC is achieved with an increased accuracy in comparison with earlier methods by the addition of iodine monochloride (Wijs reaction) to PVC coupled with x-ray fluorescence analysis to determine the iodine content of the polymer. The number of double bonds per unit weight of polymer increases on increasing the polymerization temperature and is proportional to the number of polymer molecules. It is not affected, however, by the presence of the chain transfer agent tetrahydrofuran (THF). At the technically important polymerization temperatures of 30 to 80°C and in the absence of the chain transfer agent, 0.9 double bonds per polymer molecule are found. The number of double bonds per polymer molecule is lowered using the chain transfer agent THF. These results support the theory that the chain transfer to monomer and possibly the termination reaction are coupled with the formation of terminal double bonds. Contributions by internal double bonds formed by dehydrochlorination of the polymer during polymerization are excluded by investigating the Cl^θ content of the water phase in the oxygen-free VC suspension polymerization. No hydrogen chloride is formed. In IR spectra of PVC, the stretching vibration of the double bonds is detected at 1667 cm^?1 by the correlation of the double bond contents and the intensities of the absorption bands. The stretching vibration at 1667 cm^?1is in accordance with those of model compounds with a 1-chloro-2-alkene structure.     

Vinyl Polymerization Initiated by Peroxydiphosphate. IV. Polymerization of Acrylonitrile Initiated by Peroxydiphosphate-Thioacetamide Redox System

Abstract

The kinetics of the aqueous polymerization of acrylonitrile initiated by the peroxydiphosphate-thioacetamide redox system was investigated at 35, 40, and 50°C. The rates of polymerization were measured at different concentrations of oxidant, activator, and monomer. Peroxydiphosphate alone did not initiate polymerization under deaerated and undeaerated conditions. Addition of certain water-miscible organic solvents and neutral salts depress the rate and conversion. On the basis of experimental observations of the dependence of the rate of polymerization on various variables, a suitable kinetic scheme has been proposed.     

Kinetics of Vinyl Polymerization. 1. Ceric Ion Induced Polymerization of Acrylonitrile in the Presence of Butane-1,4-diol

The kinetics of acrylonitrile polymerization initiated by butane-l,4-diol-Ce(IV) redox system have been studied in aqueous sulfuric acid in the range 30 to 40°C under nitrogen. There is no experimental evidence for the formation of a complex between diol and oxidant; the kinetics are consistent with a linear mode of termination. The effect of certain neutral salts, acids, water-miscible organic solvents, and temperature on the rate of polymerization and the rate of metal ion disappearance have also been investigated. Various rate and energy parameters have been evaluated.     

Polymerization of Vinyl Monomers Using Oxidase Catalysts

Polymerization of vinyl monomers using oxidase as catalyst has been performed under argon in the presence of acetylacetone as a mediator and without the use of hydrogen peroxide. The polymerization of acrylamide was catalyzed by a laccase or sarcosine oxidase catalyst in distilled water and efficiently produced the polymer with high molecular weight. In the polymerization using the laccase catalyst, the effects of temperature, time, and amounts of enzyme and mediator have been systematically investigated. On the other hand, various other oxidases such as bilirubin, choline, and xanthine oxidases showed no or little activity for the vinyl polymerization. The laccase/acetylacetone catalyst induced the polymerization of methyl methacrylate and styrene in a mixture of water and tetrahydrofuran. Laccase alone also acted as a catalyst for the vinyl polymerization of acrylamide and methyl methacrylate without acetylacetone. In the polymerization of methyl methacrylate using lipoxidase as the catalyst in the presence of acetylacetone, the reaction occurred in air.