Spontaneous copolymerization of 1,3-cycloheptadiene with acrylonitrile in the presence of zinc chloride

The reaction of 1,3-cycloheptadiene (1,3-CHpD) with acrylonitrile (AN) in the presence of ZnCl₂ leads spontaneously to the simultaneous formation of an alternating copolymer and a small amount of cycloadduct. The copolymer has a predominantly cis-1,4-structure. The formation of the charge—transfer complex between 1,3-CHpD and (AN)c (AN coordinated to ZnCl₂) in AN was detected by ultraviolet (UV) spectroscopy. The activation energies for the cycloaddition and for the copolymerization under the conditions used were determined to be 17.6 (in the presence of 1,1-diphenyl-2-picrylhydrazyl) and 16.3 kcal/mole, respectively. The rate of copolymerization in AN was found to depend on the 1.5th power of the concentrations of (AN)c and of 1,3-CHpD. Oxygen and UV irradiation causes an acceleration of the copolymerization only. On the basis of these results the mechanism of the spontaneous copolymerization is discussed and its relation to the cycloaddition in systems of 1,3-cyclodienes and AN in the presence of ZnCl₂ is mentioned.     

Thermal stability and flammability of butadiene- acrylonitrile rubber cross-linked with iodoform

Summary The paper discusses the results of thermal analysis and flammability of butadiene-acrylonitrile rubber, Perbunan NT 1845 of Bayer, cross-linked with iodoform. The properties of the iodoform vulcanizate have been compared with those of peroxide vulcanizate. The thermal analysis has been performed in air with use of a derivatograph under air and nitrogen atmosphere as well as dynamic scanning calorimetry (DSC). The flammability of vulcanizates has been determined by the method of oxygen index and in air. The toxicity of the thermal decomposition and combustion products of the vulcanizates under investigation has been also determined. Based on complementary examinations, DTA and DSC curves have been interpreted from the point of view of thermal transitions of the conventionally and non-conventionally cross-linked nitrile rubbers. The glass transition temperature of the cross-linked polymer both in cooling and heating has been determined.     

Study on copolymerization behavior of 2-substituted 4-methylene-1,3-dioxolane with maleic anhydride and acrylonitrile

Copolymerizations of 4-methylene-2-styryl-1,3-dioxolane ( 1 ) and 4-methylene-2-methyl-2-styryl-1,3-dioxolane ( 2 ) with electron-deficient monomers, such as maleic anhydride (MA) and acrylonitrile (AN) were investigated. Only homopolymer of 1 was obtained from the copolymerization of 1 with MA in the presence or absence of AIBN. The copolymerization of 1 and AN with AIBN as initiator gave a copolymer consisting of three kinds of repeating units. Reaction of 2 with MA gave a crystalline product with and without AIBN present. A nine-membered ring structure is proposed for this product based on its IR, UV, proton and ¹³C-NMR spectra, as well as elemental analysis. No polymer was obtained from the copolymerization of 2 and AN with or without AIBN initiator. Based on the structures of the products obtained from the copolymerization, a number of polymerization mechanisms are proposed. © 1996 John Wiley & Sons, Inc.     

Formation of alternating copolymers via spontaneous copolymerization of 1,3-dehydroadamantane with electron-deficient vinyl monomers

Copolymerizations of 1,3-dehydroadamantane, 1, and various vinyl monomers were carried out in THF at room temperature. On mixing 1 with electron-deficient vinyl monomers, such as acrylonitrile and methyl acrylate, in the absence of any initiator, the copolymerization spontaneously proceeded to give alternating copolymers in 28-88% yield. By contrast, no reaction of 1 occurred at all when isobutyl vinyl ether or styrene was mixed under similar conditions. These contrastive results indicate the high electron density of a central sigma-bond in a strained [3.3.1]propellane derivative, 1. Alternating sequences of the resulting copolymers were characterized by NMR and MALDI-TOF-MS measurements. DSC and TGA measurements revealed the high thermal stability of the alternating copolymers containing bulky, stiff, and strain-free adamantane skeletons.     

Alternating copolymerization of isoprene and butadiene with acrylonitrile

Copolymerizations of acrylonitrile and isoprene or butadiene were carried out in the presence of a new catalytic system containing Cr(O-tert-Bu)₄ and AlEtCl₂. It was found that the copolymer compositions have a highly alternating structure, even with varying feed ratios of monomer. The nuclear magnetic resonance spectra of the copolymers obtained with this catalytic system were observed and are discussed in terms of the alternation.     

Facile synthesis of functional polyperoxides by radical alternating copolymerization of 1,3‐dienes with oxygen

We have developed a facile synthesis of degradable polyperoxides by the radical alternating copolymerization of 1,3‐diene monomers with molecular oxygen at an atmospheric pressure. In this review, the synthesis, the degradation behavior, and the applications of functional polyperoxides are summarized. The alkyl sorbates as the conjugated 1,3‐dienes gave a regiospecific alternating copolymer by exclusive 5,4‐addition during polymerization and the resulting polyperoxides decomposed by the homolysis of a peroxy linkage followed by successive β‐scissions. The preference of 5,4‐addition was well rationalized by theoretical calculations. The degradation of the polyperoxides occurred with various stimuli, such as heating, UV irradiation, a redox reaction with amines, and an enzyme reaction. The various functional polyperoxides were synthesized by following two methods, one is the direct copolymerization of functional 1,3‐dienes, and the other is the functionalization of the precursor polyperoxides. Water soluble polyperoxides were also prepared, and the LCST behavior and the application to a drug carrier in the drug delivery system were investigated. In order to design various types of degradable polymers and gels we developed a method for the introduction of dienyl groups into the precursor polymers. The resulting dienyl‐functionalized polymers were used for the degradable gels. The degradable branched copolymers showed a microphase‐separated structure, which changed owing to the degradation of the polyperoxide segments. © 2009 The Japan Chemical Journal Forum and Wiley Periodicals, Inc. Chem Rec 9: 000–000; 2009: Published online in Wiley InterScience ( www.interscience.wiley.com ) DOI 10.1002/tcr.200900009     

Graft copolymerization of acrylonitrile onto polystyrene

It is possible to graft vinyl monomers, such as acrylonitrile, onto polystyrene via anionic processes but not by a radical process. Both homopolymerization of the added acrylonitrile and graft copolymerization in which acrylonitrile units are added to the para position on the benzene ring in styrene occur; the conversion of acrylonitrile into polymer depends upon the time and temperature of the reaction and on the concentration of the anionic initiator, butyllithium. A constant 15–20% of the acrylonitrile is converted to graft copolymer while the remainder is homopolymerized; graft copolymer may be separated from homopolymer by selective precipitation from either N,N′-dimethylformamide or aqueous potassium thiocyanate. Treatment of the mixed graft and homopolymer with aqueous sodium hydroxide converts the nitrile into an acid salt and one may conveniently separate homopolymer from graft copolymer in this way. Each polystyrene chain is grafted with acrylonitrile units. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 1275–1282, 1997     

Vibrational spectrum and structure of the second stable rotamer of butadiene-1,3

The dependence of the calculated vibrational frequencies of the second stable rotamer of butadiene- 1,3 on the torsional angle about the central single C---C bond has been studied in the interval from 0° (planar syn-form) to 50°. The force field was described by scaled force constants obtained from CNDO/2 calculations. The best agreement between the calculated and experimental vibrational frequencies was found at 25° from the planar syn-form. The results of the vibrational frequency calculations for this configurations of some isotopomers of butadiene- 1,3 are given. In addition, in the light of the theoretical results obtained and new experimental evidence, the assignment of certain out-of-plane normal modes of the anti-form of C₄D₆ is also discussed.     

Thermal copolymerization of acrylonitrile with methacrylate units arranged in matrix

Copolymerization of acrylonitrile with methacrylates on a matrix has been examined (using methacrylate of p-cresol-formaldehyde resin). It has been found that the copolymerization proceeds at 70° without an initiator. The reactivity ratios depend on the length of the matrix used. The method of calculating Q and e according to the Alfrey-Price scheme has been discussed for the system under investigation.     

Radical alternating copolymerization of vinyl ethers

New alternating equimolar copolymers of electrophilic trisubstituted ethylenes, methyl 3-phenyl-2-cyanopropenoate and 2-phenyl-1,1-dicyanoethene, with ethyl, n-butyl, i-butyl, t-butyl, 2-chloroethyl, and phenyl vinyl ethers were prepared by free radical initiation. Chemical compositions of the copolymers are 1 : 1 in broad ranges of monomer ratios. The copolymerization rate of both electrophilic monomers with the vinyl ethers increase in the series 2-chloroethyl > ethyl > phenyl > n-butyl > i-butyl > t-butyl. These variations in the reactivity of the vinyl ethers are discussed in terms of their preferred conformations in donor-acceptor complexes with electrophilic trisubstituted ethylenes. © 1993 John Wiley & Sons, Inc.     

Radiation induced graft copolymerization of acrylonitrile on natural rubber

Acrylonitrile graft natural rubber was prepared by initiating the polymerization of acrylonitrile in natural rubber field latex using γ-rays. The reaction was carried out at different rubber-monomer concentrations and the properties of the modified rubbers were compared with those of natural rubber and nitrile rubber.     

Chain transfer studies of alternating copolymerization

Dimethylaniline (DMA) induces chain transfer in the zinc bromide-complexed donor–acceptor polymerizations of styrene–acrylonitrile to form alternating copolymers. The Mayo plots are linear, but the rates decrease with increase in DMA and degradative chain transfer occurs. Although conventional free-radical transfer agents have negligible effect on the rates or molecular weights, a twentyfold reduction of molecular weight is obtained with DMA. Spectroscopic data indicate the formation of an equimolar complex of DMA and ZnBr₂, but the lowering of molecular weight is not attributable to the reduction of the effective ZnBr₂, concentration. A possible mechanism involving a competition between [ZnBr₂(DMA)₂] and [ZnBr₂,DMA,AN] is suggested.     

Reaction mechanism of the alternating copolymerization of aziridines with cyclic imides

The copolymerizations of N-substituted aziridines and cyclic imide were studied. N-Ethylsuccinimide copolymerized with ethylenimine, but N-ethylethylenimine did not copolymerize with succinimide and N-ethylsuccinimide without catalyst. The effect of additives on the copolymerization of ethylenimine with succinimide and that of N-ethylethylenimine with succinimide and N-ethylsuccinimide was also examined. The rate of copolymerization of ethylenimine with succinimide was accelerated by the addition of N-acetylethylenimine or water. The copolymerization of N-ethylethylenimine with succinimide was initiated only by water, but N-ethylethylenimine did not copolymerize with N-ethylsuccinimide in the presence of water. Gas evolved on heating the copolymer of ethylenimine and succinimide was analyzed and confirmed to be ammonia. On the basis of these results the reaction mechanisms of the copolymerization of ethylenimine with succinimide or N-ethylsuccinimide and of N-ethylethylenimine with succinimide initiated by water are discussed.     

Semicontinuous heterophase copolymerization of styrene and acrylonitrile

The synthesis of styrene‐acrylonitrile copolymers by semicontinuous heterophase polymerization is reported here. The effect of feed composition at a fixed addition rate of monomer mixture on kinetics, particle size, polymer content, and molar masses, was studied. This process permits the synthesis of nanolatexes containing narrow size‐distribution particles with number‐average diameter (D_n) of about 18 nm, polymer content as high as 23 wt %, and copolymer‐to‐surfactant weight ratios between 23 and 25, depending on monomer feeding rate, which are larger than those reported for microemulsion copolymerization of several comonomers. Copolymers with homogeneous composition similar to the feeding monomers composition were obtained thorough the reaction, which is difficult to achieve by batch polymerization. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Influence of butadiene-1,3 on ethanal pyrolysis at 495°C

At 495°C and a low extent of reaction, ethanal pyrolysis is slightly inhibited by the addition of small quantities of butadiene-1,3, whereas it is accelerated by more important quantities. The inhibiting effect is interpreted in terms of a free-radical chain mechanism in which the main chain carriers of ethanal pyrolysis (CH₃.free radicals) reversibly add to butadiene-1,3 and yield penten-2-yl (R.) free radicals. These free radicals either react in a metathetical step: or in terminating steps. But butadiene-1,3 also gives rise to new initiation steps: which account for the accelerating effect. Process (i₃) seems to be more important than process (i₂) in the experimental conditions, but its nature could not be identified. The results are consistent with literature data and the following value of k₆: (4.57T in cal/mol).