Spontaneous polymerization of acrylamide in glycerol: Active centers and specific features

The nature of active centers and the specific features of the spontaneous polymerization of acrylamide in glycerol in the range 300-77 K have been studied. Glycerol activation is needed for polymerization. At this stage, active intermediate species are formed and stabilized under the action of photo-and γ radiation. Intermediate species are hydroperoxide compounds resulting from the sensitized (through technical traces) photolysis (or radiolysis) of glycerol. The decomposition of hydroperoxides into radicals on addition of finely dispersed acrylamide powder into the activated glycerol yields primary acrylamide radicals that initiate the growth of polymer chains.     

Low-temperature radical polymerization of acrylamide in ethanol and glycerol under the action of molecular chlorine

It is shown by means of calorimetry, IR and EPR spectroscopy, elemental analysis, chromatography, and viscosimetry that radicals formed during the low-temperature action of molecular chlorine on acrylamide or its solutions in ethanol or glycerol initiate the polymerization reaction of acrylamide. It is established that during the low-temperature chlorination of pure acrylamide, polymerization takes place in the temperature range of 180–210 K with a polymer yield of ∼10%. The low-temperature chlorination of 20% solutions of acrylamide in ethanol or glycerol was performed to increase the product yield. It is shown that the low-temperature chlorination of acrylamide solution in glycerol increases the polymer yield by a factor of approximately two, and the content of chlorine in it falls by a factor of around ten. The low-temperature chlorination of acrylamide solution in ethanol did not lead to an increase in the polymer yield. A small reduction was noted in the chlorine content of the polymer.     

Spontaneous polymerization of acrylamide in glycerol

The spontaneous polymerization of acrylamide in glycerol in the range of 250–350°C has been first observed and investigated. It has been shown that the polymerization proceeds during dissolution of acrylamide in glycerol and leads to formation of gel globules in which the growth of polymer chains takes place. The reaction occurs without termination of kinetic chains in the living polymerization mode. The effective chain transfer at a low concentration of active centers ensures a high yield of the polymer.     

Catalytic action of metallic salts in autoxidation and polymerization. VIII. Polymerization of methyl methacrylate by various metal acetylacetonate–cyclic ether hydroperoxides

Polymerization of methyl methacrylate by cyclic ether hydroperoxide–metal acetylacetonate systems for a number of different metals was carried out to compare with the tert-butyl hydroperoxide–metal acetylacetonate initiating systems. The rate of polymerization of methyl methacrylate with cyclic ether hydroperoxides as initiating systems was much higher than that with tert-butyl hydroperoxide. In cyclic ether hydroperoxide initiating systems, V(III), Co(II,III), Fe(III), Cu(II), and Mn(II) promoted the polymerization rate markedly, and Zn(II), Ni(II), Al(III), and Mg(II) had little or no effect; in the tert-butyl hydroperoxide initiating system only V(III), Co(II), and Mn(II) enhanced polymerization rate, and most of other metals showed little or no effect. Furthermore, noticeable differences in color of solution and appearance during polymerization, and in relation between conversion and the degree of polymerization were observed. The effect of metal acetylacetonates on hydroperoxide initiators in polymerization of methyl methacrylate was also compared with that on the decomposition of hydroperoxides.     

反应介质对N,N-二乙基二硫代氨基甲酸苄酯引发丙烯酰胺聚合反应的影响

The effects of reaction medium (alcohol, dioxane, dioxane/alcohol)on the heterogenous polymerization of acrylamide initiated by BDC (benzyl diethyldiothiocarbate)were studied. The results showed that herterogenous polymerization differed from homogeneous solution polymerization initiated by BDCand did not have the character of living radical polymerization. The polarity of reaction medium affected the enolization of acrylamide obviously, and made the yield of polymer and molecular weight different from each other, behaving obvious solvent effects.The UVspectra of products and polymerization of acrylamide initiated by products, show that iniferter functional groups remained in products.     

反应介质对N，N－二乙基二硫代氨基甲酸苄酯引发丙烯酰胺聚合反应的影响

反应介质对Ｎ，Ｎ－二乙基二硫代氨基甲酸苄酯引发丙烯酰胺聚合反应的影响杨文君，沈家骢（青岛化工学院橡塑工程研究所，青岛，２６６０４２）（吉林大学化学系）关键词聚丙烯酰胺，溶剂效应，自由基聚合，引发－转移－终止剂近年来，具有结构的有机硫化物以其优良的Ｉｎ...     

Polymerization of methyl methacrylate by resin containing polyethylenepolyamine side chain–peroxide system

Macroreticular resins (RST) bearing polyethylenepolyamine side chain were prepared by the amination of the chloromethylated macroreticular styrene—divinylbenzene copolymer beads. The polymerization of methyl methacrylate (MMA) was carried out in a water—organic solvent mixture containing hydroperoxide and RST. The polymerization of MMA proceeded smoothly in the presence of both hydroperoxide and RST. The presence of water was indispensable for this polymerization. 1,4-Dioxane hydroperoxide showed a high activity for the polymerization of MMA. The polymerization of MMA by this system was greatly affected by the structure of the resins. It was especially accelerated by using macroreticular resins with appropriate porosities.     

Preparation of carboxyl‐end‐group polyacrylamide with low polydispersity by ATRP initiated with chloroacetic acid

Atom transfer radical polymerization (ATRP) of acrylamide was successfully carried out with chloroacetic acid as initiator and CuCl/N,N,N′,N′‐tetramethylethylenediamine (TMEDA) as catalyst either in water at 80 °C or in glycerol–water (1:1 v/v) medium at 130 °C. In both cases, carboxyl‐end‐group polyacrylamide was obtained with lower polydispersity ranging from 1.03 to 1.44 depending on the polymerization condition. Polymerization kinetics showed that the polymerizations proceeded with a living/controlled nature and accelerated at a higher temperature. The effect of pH in the reaction system on the polymerizations was further studied, revealing that chloroacetic acid not only served as a functional initiator for the ATRP of acrylamde but also provided the acidic polymerization condition, which effectively protected the ATRP of acrylamide from the unexpected complexation and cyclization side‐reactions. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 3956–3965, 2007     

过硫酸盐与吡咯烷体系引发丙烯酰胺聚合反应机理的研究

我们曾经报道过硫酸盐和脂肪族六元环胺可以组成氧化还原引发体系用于烯类单体水溶液聚合,并且证实环仲胺如吗啉(MP)和哌啶(PD)被氧化后生成氮自由基参与了引发反应。本文对过硫酸盐和五元环胺吡咯烷(PyD)组成的引发体系进行了研究。 1 实验部分     

Coordinated radical polymerization and redox polymerization of acrylamide by ceric ammonium nitrate

The ceric salt-initiated polymerization on acrylamide and graft copolymerization of acrylamide onto cellulose were studied. The mechanism of the ceric salt-initiated polymerization of acrylamide in the homopolymerization system can be explained by a radical mechanism based upon Ce⁴⁺-coordinated acrylamide, and the mechanism of the ceric salt-initiated graft copolymerization of acrylamide onto cellulose can be explained in two ways: a free-radical mechanism with the ceric—cerous redox system, and a radical mechanism based upon Ce⁴⁺-coordinated acrylamide. The velocities of initiation, propagation, and termination in the redox mechanism are quite different from those in the coordinated radical mechanism. From the infrared absorption and nuclear magnetic resonance spectra measurements it is concluded that the structure of the ceric-coordinated acrylamide is the π-complex.     

Kinetics of styrene homogeneous polymerization to atactic polypropylene

The rate of polymerization of styrene initiated by hydroperoxidized atactic polypropylene in a homogeneous toluene solution has been measured at 60 and 70°C. The reaction is first-order with respect to styrene concentration and independent of the polymeric hydroperoxide concentration above 2 × 10^?5N hydroperoxide. The individual rate constants, length and frequency of the grafted polystyrene chains along the polypropylene backbone have been calculated and their significance discussed. The initiation rate constant compares closely with values reported for the analogous tert-butyl hydroperoxide-initiated polymerization. The rate constant for the chain transfer termination elementary step at 70°C., however, is 18 times the value reported for the tert-butyl hydroperoxide-initiated polymerization of styrene. This high constant accounts for the relatively low rates of polymerization observed and high termination rates. Chain deactivation is presumably accelerated by increased collisions between growing styrene chains and inactive propylene hydroperoxide and polystyrene molecules. Distribution of polystyrene grafts on polypropylene is estimated from knowledge of effects of styrene concentration, polymeric hydroperoxide concentration, and temperature upon the rate of polymerization.     

Thermal polymerization of acrylamide during the formation of the structures of acrylamide complexes with metal nitrates

The effects of the composition of Mn^II, Co^II or Ni^II nitrate hydrate — acrylamide (AAM) mixtures and of the duration of their aging at ambient temperature on the structurization of acrylamide complexes and on the character of their thermal polymerization have been studied by scanning and isothermic differential calorimetry. Structurization is a rather prolonged step in the synthesis of acrylamide complexes. The peculiarities and rate of this step are determined by the composition of the mixture and by the nature of the complexforming compound; it yields several structural modifications of the AAM complexes. The thermal polymerization of those structural forms of acrylamide complexes that polymerize at low temperatures may be formally described as polymerization in an acrylamide-nitrate-water mixture. The effective activation energy of the polymerization of acrylamide mixed with Mn^II nitrate hydrate is 45 kJ mol^–1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 679–683, April, 1995.This work was carried out with financial support from the Russian Foundation for Basic Research, Project No. 93-03-4162.     

Heterogeneous initiators for the synthesis of polymer nanocomposites

Nanocomposites are obtained by the radical polymerization of styrene and methyl methacrylate on the surface of a dispersed filler containing chemisorbed compounds of quaternary ammonium, which catalyze decomposition of cumene hydroperoxide. The heterogeneous catalysts of hydroperoxide decomposition are obtained via the adsorption of cetyltrimethyl ammonium bromide and acetylcholine chloride on sodium montmorillonite, cellulose, and chitosan. The highest rate of the polymerization of both monomers is provided by the cellulose–cetyltrimethyl ammonium bromide catalyst. For a more hydrophilic methyl methacrylate, the rate of radical initiation is significantly lower at the same concentrations of the catalyst and hydroperoxide compared with hydrophobic styrene; however, the rate of polymerization is higher than for styrene because of a higher activity of methyl methacrylate in chain-propagation reactions. Relatively high rates of radical generation upon contact of cellulose–cetyltrimethyl ammonium bromide and cellulose–acetylcholine with hydroperoxides open the possibility to create cellulose-based disinfecting and medical materials.     

过硫酸钾引发丙烯酰胺微乳液聚合

以山梨醇酐单月桂酸醋（Ｓｐａｎ２０）和聚氧乙烯山梨醇酐单硬醋酸酯（Ｔｗｅｅｎ６０）的混合物为乳化剂制备丙烯酰胺微乳液，研究了体系中Ｔｗｅｅｎ６０浓度、水相丙烯酰胺浓度对微乳液电导行为的影响．用过硫酸钾引发微乳液聚合，发现聚合开始后，体系电导率迅速下降，在聚合进入恒速期后电导不再降低．聚合的动力学表达式为：Ｒｐ∝［ＡＭ］１．１７［Ｅ］－１．２６［Ｉ］０．５；Ｍｖ∝［ＡＭ］１．０５［Ｅ］－０．９４［Ｉ］－０．６２．它与常规乳液聚合的动力学相差较大，却类似于悬浮聚合．     

Polymerization of vinyl monomers in the water–1,4-dioxane system containing peroxide and water-soluble polymer

Water-solube polymer (PST) containing triethylenetetramine side chain was prepared by the amination of chloromethylated polystyrene with triethylenetetramine in 1,4-dioxane. The polymerization of vinyl monomers was carried out in the water–organic solvent system containing PST and a very small amount of peroxide. The polymerization of methyl methacrylate proceeded smoothly in the presence of both peroxide and PST. It was found that the polymerization was initiated with the radicals generated by the interaction between hydroperoxide and amino groups of PST. 1,4-Dioxane hydroperoxide showed a high activity for the polymerization of methyl methacrylate. The maximum rate of the polymerization was observed at 60°C and in an approximately neutral solution. The addition of suitable amount of Cu(II) accelerated the polymerization of methyl methacrylate. The selective polymerization of vinyl monomers was observed in this system.     

锰(Ⅲ)离子与羧酸或α-羟基羧酸体系引发丙烯酰胺聚合

锰(Ⅲ)离子可以引发烯类单体自由基聚合。羧酸,α-羟基羧酸对丙烯酰胺聚合有促进作用,其活性顺序为羟基多元羧酸(柠檬酸)>羟基羧酸(乳酸)>羧酸(正丁酸)。测定了在较高酸性([H~+]=3.0M)的硫酸水溶液中,单独Mn~(3+),Nn~(3+)-乙醇酸,Mn~(3+)-乳酸引发丙烯酰胺聚合的活化能与动力学方程。     

Electroinitiated polymerization of acrylamide by direct electron transfer

Electroinitiated polymerization of acrylamide was carried out in acetonitrile–tetrabutylammonium fluoroborate by electrolytic reduction of monomer. It was shown by cyclic voltammetry that direct electron transfer from the cathode to the monomer can be achieved in this solvent–electrolyte system. Reduction peak potentials measured by cyclic voltammetry indicated that sodium salts will interfere with such a mechanism. Since the reduction peak potential of sodium salt and dimethylformamide are found to be lower than acrylamide, this couple was not employed for polymerization in this work. Acetonitrile–tetrabutylammonium fluoroborate couple is stable at the reduction peak potential of acrylamide.     

Polymerization of acrylamide in inverse microemulsions under special conditions

Increasing of Φ_aw, the volume fraction of the aqueous phase (water + acrylamide) in inverse microemulsion systems toluene / sodium bis(2-ethylhexyl) sulfosuccinate (AOT) / water / acrylamide (Set A); toluene / AOT / water / acrylamide / sodium dodecyl sulfate (SDS) (Set AD) and toluene / styrene/ AOT / water / acrylamide (Set AS) leads to an increase of the viscosity. The dependence of the viscosity on Φ_aw in the temperature range 20–45°C is characterized by three maxima (at Φ_awΦ25, 45 and 65%). These maxima can be eliminated by an increase of temperature to 50°C (Sets A and AS). The most prominent peak (at Φ_awΦ45%) is preserved at 50°C only for systems of Set AD. The acrylamide polymerization behaviour in Sets A and AD is very similar irrespective of the nature of initiator used (dibenzoyl peroxide and ammonium peroxodisulfate). The rate of polymerization is a complex function of Φ_aw. In the presence of styrene (Set AS) a significant retardation of polymerization was observed. The rate of polymerization increases with increasing Φ_aw. Viscosity of the inverse dispersion system (Set AD) has no effect on the polymerization rate of acrylamide.     

Synthesis of surfactant‐free carbon nanotube/poly(styrene‐co‐acrylamide) by dynamic interfacial emulsion polymerization under sonication

This paper describes a study on emulsifier‐free ultrasonically assisted in‐situ copolymerization method of acrylamide and styrene in the presence of CNT, resulting in stable and uniform dispersions. The dispersions prepared were found stable for several months. Thermogravimetric analysis (TGA) curves and conversion measurements provided an insight regarding the polymerization mechanism and the nanocomposites structure. Films prepared of the polymerization products resulted in some clear and transparent coatings. The polymerization method described is simple and very fast compared with the other literature reported methods. TGA was extensively used as an analytical tool for determination of the composition of acrylamide–styrene copolymers. TGA and differential scanning calorimetry indicate that the polymerization product is largely a poly(styrene‐co‐acrylamide), where the acrylamide fraction is attached to the CNT surfaces. The copolymer produced, with and without CNT, is essentially a block copolymer, where each block contains small amounts of the other comonomer. To the authors' best knowledge, this report is the first one describing the production of stable dispersions of CNT in surfactant‐free poly(styrene‐co‐acrylamide) emulsion. Copyright © 2013 John Wiley & Sons, Ltd.     

Effect of the number of seed polymer particles on the kinetic behavior of the seeded emulsion copolymerization of styrene and acrylamide

The seeded emulsion copolymerizations of styrene and acrylamide were carried out at 50°C using polystyrene latex particles as the seed and potassium persulfate as the initiator, respectively. It was found that the change in the number of seed particles initially charged causes a drastic change in the kinetic behavior of this seeded emulsion copolymerization system: when the number of seed particles initially charged was less than a certain critical value, both styrene and acrylamide started polymerization from the beginning of the reaction. However, when the number of seed particles was higher than this critical value, an apparent induction period suddenly emerged only for acrylamide polymerization, that is, acrylamide did not start polymerization until the styrene conversion exceeded around 75%, while the styrene polymerization started and continued very smoothly from the beginning of the reaction. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35 : 2689–2695, 1997