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  • 1965-1969  (18)
  • Physics  (18)
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  • 1
    Electronic Resource
    Electronic Resource
    NMR studies on the stereospecific polymerization of methyl vinyl ether. Part II. Polymerization by sulfuric acid-aluminum sulfate complex: Enantiomorphic catalyst sites model (1967)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 5 (1967), S. 863-875 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Highly crystalline poly(methyl vinyl ether) (PMVE) was produced in toluene in a temperature range of 0 to -20°C. with the use of sulfuric acid-aluminum sulfate complex (SA catalyst). It was found from the NMR spectra that these polymers contained more than 50% of the triad isotactic fraction and the melting point of the unfractionated polymer was about 130°C. However, PMVE containing a large amount of the isotactic fraction was insoluble in nitromethane, so the triad tacticity of highly crystalline PMVE could not be quantitatively determined. The molecular weight of PMVE increased with increasing conversion and increasing polymerization temperature. This behavior is different from that in metal halide catalysts. Also, the stereoregularity of PMVE decreased with increasing monomer concentration. However, addition of a polar solvent and increasing the polymerization temperature had little effect on the stereoregularity of the polymer. The increase in the isotactic fraction at high catalyst concentration and the difference in the monomer composition in the copolymerization of methyl vinyl ether with 2-chloroethyl vinyl ether by SA catalyst from that obtained by BF3·O(C2H5)2 suggest that the absorption of MVE on a catalyst surface is an important step in the propagation step by SA catalyst. The fraction of the triad tacticity calculated from the enantiomorphic catalyst sites model8 coincided with the experimental results. This fact shows that the steric structure of the adding monomer is determined only by the nature of the catalyst irrespective of the nature of a growing chain end. It is concluded, on considering also the results of the previous paper, that completely different factors can control the steric structure of a polymer even for the same monomer when different catalysts are used.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1967.150050413
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  • 2
    Electronic Resource
    Electronic Resource
    NMR studies on the stereospecific polymerization of methyl vinyl ether. Part I. Polymerization by metal halides: Penultimate effect (1967)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 5 (1967), S. 849-862 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Methyl vinyl ether (MVE) was polymerized under various conditions by BF3·O(C2H5)2 and SnCl4·CCl3CO2H catalysts. The effect of polymerization conditions on the steric structure of poly(methyl vinyl ether) (PMVE) was studied by NMR spectra. It was found that the triad isotacticity of PMVE decreased and the syndiotacticity and heterotacticity increased with increasing polarity of the solvent and increasing polymerization temperature. This result coincided with the qualitative conclusion estimated from softening point and infrared spectra. However, the variation of tacticity by the change of the polarity of a solvent was not so large as expected. There was no large difference between the behavior of BF3·O(C2H5)2 and SnCl4·CCl3CO2H as catalysts. From the relation between the difference of free energy of monomer addition due to the steric structure of the polymer and the polymerization temperature, it was concluded that the penultimate effect really existed and was due to only the difference in enthalpy in the MVE-BF3. O(C2H5)2 or MVE-SnCl4·CCl3CO2H systems. The penultimate effect was not greatly changed by the polymerization conditions in these systems.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1967.150050412
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  • 3
    Electronic Resource
    Electronic Resource
    Cationic polymerization of cyclic olefins (1966)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 4 (1966), S. 869-879 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The polymerization and the polymerizabilities of indene, benzofuran, and 1,2-dihydronaphthalene are discussed from the point of view of ring strain, ring stabilization, and steric hindrance in the transition state. Monomer reactivities of these olefins were estimated from copolymerization with styrene and from the rate of addition of iodine bromide in acetic acid. Rates and degrees of polymerization are compared with monomer reactivities and resonance energies of indene, 1,2-dihydronaphthalene, and benzofuran as a measure of ring strain and stabilization. It is found that indence is 1.5-2.0 times more reactive than styrene. This high reactivity of indene is attributed to the ring strain in the monomer state and to the low amount of steric hindrance in the transition state of the coplanar five-membered cyclic olefin. 1,2-Dihydronaphthalene is strained and therefore reactive, but propagation to higher molecular weight products is impeded due to the steric hindrance. The reactivity of benzofuran is decreased by conjugative stabilization of C=C double bonds at the reaction site.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1966.150040413
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  • 4
    Electronic Resource
    Electronic Resource
    Polymerization of tetraoxane at low concentration catalyzed by BF3·O(C2H5)2 (1967)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 5 (1967), S. 2997-3007 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: In the solution polymerization of tetraoxane catalyzed by BF3·O(C2H5)2, trioxane and methanol-insoluble polymer were produced. However, the amounts of these products depend on the nature of solvent used. A critical concentration of tetraoxane is observed for the formation of methanol-insoluble polymer; at less than this critical concentration of tetraoxane no methanol-insoluble polymer is obtained, but trioxane is preferentially produced. This critical concentration of tetraoxane is higher in a more polar solvent, so the amount of methanol-insoluble polymer produced decreases and the amount of trioxane produced increases with increasing the polarity of solvent used. These results may be explained in terms of a stabilization of the active center leading to formation of trioxane by a solvation with solvent.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1967.150051203
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  • 5
    Electronic Resource
    Electronic Resource
    Cationic polymerization of the geometrical isomers of β-methylstyrene and anetholeThis is the sixth in a series of papers, “Cationic Polymerization of α,β-Disubstituted Olcfins.” (1968)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 6 (1968), S. 1825-1832 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Cationic polymerization of the geometrical isomers of β-methylstyrene and anethole (p-β-methoxy-β-methylstyrene) was studied in order to clarify the relation between the geometrical structure of the α,β-disubstituted olefins and their monomer reactivities, subsequent to previous work. Polymerization was carried out in toluene or ethylene dichloride with stannic chloride at 0°C. trans-β-Methylstyrene was 1.3 to 1.5 times more reactive than cis-β-methylstyrene to the styrene carbonium ion; copolymerization between the trans and the cis isomers of β-methylstyrene showed little difference in monomer reactivity. By contrast, the cis anethole was 1.5-2.0 times more reactive than the trans, according to copolymerization between the two isomers together. The lower reactivity of the cis-β-methylstyrene could be explained by steric hindrance in the cis isomer, proposed by Overberger et al.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1968.150060704
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  • 6
    Electronic Resource
    Electronic Resource
    Solution polymerization of trioxane catalyzed by stannic chloride (1968)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 6 (1968), S. 3031-3040 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The polymerization of trioxane catalyzed by stannic chloride (SnCl4) in ethylene dichloride was studied and compared with the results obtained with boron trifluoride etherate, BF3·O(C2H5)2, as catalyst. Under the same conditions, the polymerization rate was larger with SnCl4 than with BF3·O(C2H5)2, while at a fixed polymer yield the molecular weight of the polymer obtained by SnCl4 was lower than with the BF3·O(C2H5)2 catalyzed reaction. The overall activation energy of trioxane polymerization with SnCl4 was 11.0 ± 0.8 kcal/mole. The kinetic orders of catalyst and monomer were determined to be close to 2 and 4, respectively. A certain amount of tetraoxane was also produced in an early stage of the polymerization with SnCl4 similar to BF3·O(C2H5)2-catalyzed reaction. However, the maximum amount of tetraoxane produced at 30°C was larger with SnCl4 than with BF3·O(C2H5)2. In addition, a ten-membered ring compound (pentoxane) was isolated in the solution polymerization of trioxane catalyzed by both SnCl4 and BF3·O(C2H5)2. The confirmation of pentoxane formation is strong evidence for the back-biting reaction mechanism.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1968.150061107
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  • 7
    Electronic Resource
    Electronic Resource
    Copolymerization of tetraoxane with styrene catalyzed by BF3·O(C2H5)2 (1967)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 5 (1967), S. 1937-1949 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The copolymerization of tetraoxane with styrene catalyzed by BF3·O(C2H5)2 was studied at 30°C. to determine whether a cyclic monomer can copolymerize with a vinyl monomer. The formation of the copolymer was confirmed by elementary analysis of both benzene-soluble and benzene-insoluble fractions of the polymer obtained. It was found by gas chromatography that a fairly large amount of 4-phenyl-1,3-dioxane and a small amount of trioxane were formed in the present system, in addition to polymers. Roughly a third of the total amount of the monomers reacted was consumed in the formation of methanol-insoluble polymer, a third for 4-phenyl-1,3-dioxane, and another third for trioxane and unknown products which could not be indentified. The formation of these cyclic compounds during the copolymerization may be explained in terms of a back-biting (or intramolecular transacetalization) reaction. The cationic reactivity of tetraoxane was found to be similar to that of styrene on the basis of both the consumption rate of each monomer in the copolymerizing system and the composition of the methanol-insoluble polymer obtained.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1967.150050811
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  • 8
    Electronic Resource
    Electronic Resource
    Stereospecific polymerization of α-methylstyrene by friedel-crafts catalysts (1966)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 4 (1966), S. 923-931 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The relationship between stereoregularity and polymerization conditions of α-methylstyrene has been studied by means of NMR spectra. The effects of solvents and various Freidel-Crafts catalysts have been investigated. The stereoregularity of poly-α-methylstyrene increased with increased polymer solubility in the solvent used and with decreasing polymerization temperature. This behavior is completely different from the stereospecific polymerization of vinyl ethers and methyl methacrylate in homogeneous systems. This may be due to the strong steric repulsion exerted by the two substituents in the α-position of α-methylstyrene. For example, with BF3 · O(C2H5)2 as catalyst at -78°C., atactic polymer is obtained in n-hexane, a nonsolvent for α-methylstyrene, whereas highly stereoregular polymer is produced in toluene or methylene chloride, good solvents for the polymer. However, the polarity of the solvent and the nature of the catalyst hardly affect the stereoregularity of the polymer.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1966.150040418
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of solvent on the amount of tetraoxane produced in the solution polymerization of trioxane catalyzed by BF3·O(C2H5)2 (1967)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 5 (1967), S. 2989-2996 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The amounts of tetraoxane produced in the polymerization of trioxane catalyzed by BF3·O(C2H5)2 were measured in various solvents. The maximum amount of tetraoxane produced depends on the nature of solvent used. This amount was independent of the initial concentration of the catalyst in ethylene dichloride and in nitrobenzene. On the other hand, in benzene, the amount of tetraoxane produced decreased slightly with increasing initial catalyst concentration. This result was explained by the reaction of tetraoxane produced with the residual catalyst as well as with the active center. The maximum amount of tetraoxane produced decreased, other conditions being similar, in the order, nitrobenzene 〉 ethylene dichloride 〉 benzene solvent. This order may be explained in terms of a longer lifetime of the active center in the more polar solvent, leading to the formation of tetraoxane.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1967.150051202
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  • 10
    Electronic Resource
    Electronic Resource
    Cationic polymerization of α,β-disubstituted olefins. Part 12. Theoretical consideration of the reactivities of vinyl ethers and β-substituted vinyl ethers (1969)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 7 (1969), S. 3129-3141 
    Details
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: To elucidate the propagation mechanism in the cationic polymerization of vinyl ethers and β-substituted vinyl ethers, the electron distribution in these monomers was computed by the extended Hückel method. Propylene and styrene derivatives were also studied in comparison with the vinyl ether derivatives. Attempts were made to explain the experimental results by various calculated reactivity indices. With the unsaturated hydrocarbons, the reactivity indices on the β-carbon parallel with the relative reactivity in the cationic polymerization or oligomerization. This agreement suggests that the transition state for the rate-determining step of the propagation reaction is represented by a model in which the carbonium ion interacts with the β-carbon of a monomer. On the other hand, the effect of β-alkyl or alkoxyl groups on the reactivity of vinyl ethers could not be explained by the model in which the carbonium ion interacts with an olefinic carbon or an ether oxygen, or both with two atoms. The following model was proposed on the basis of the electronic stabilization energy due to the de- localization from the occupied orbital of a monomer to the vacant orbital of a carbonium ion. This model can explain reasonably the relative reactivity of vinyl ethers and β-substituted vinyl ethers observed in the cationic copolymerization catalyzed by BF3·O(C2H5)2.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1969.150071109
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