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  • Chemistry  (10)
  • 1
    Electronic Resource
    Electronic Resource
    Block copolymers obtained by free radical mechanism. II. Butyl acrylate and methyl methacrylate (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 26 (1981), S. 3103-3115 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Block copolymers were synthesized using methyl methacrylate and butyl acrylate as the monomers and a multifunctional initiator, di-t-butyl 4,4'-azobis(4-cyanoperoxyvalerate). The polymerizations for the formation of the block copolymers were carried out in two stages. First the poly(methyl methacrylate) polymeric initiator was synthesized and isolated. In the second stage, the thermallyactivated azo group in the polymer backbone initiated the polymerization of butyl acrylate. Upon termination by combination a tri-block results. Selective solvent fractionation was used to separate the block from the homopolymers.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1981.070260924
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  • 2
    Electronic Resource
    Electronic Resource
    Synthesis of polystyrene-block-polyoxyethylene for use as a stabilizer in the emulsion polymerization of styrene (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 1925-1933 
    Details
    ISSN: 0887-624X
    Keywords: polymeric surfactant ; polymeric stabilizers ; amphipathic block copolymers ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Five well-defined polystyrene-block-polyoxyethylene copolymers were synthesized by anionic polymerization for use as stabilizers in the emulsion polymerization of styrene. The size of the blocks and their relative weight ratios to each other were the main variables. The molecular weights of the blocks varied from M̄n = 1000-7000 for polystyrene, and M̄w = 3000-9000 for polyoxyethylene. The results of the styrene emulsion polymerization with these block copolymers as stabilizers indicate that for efficient anchoring the block length need not be more than 10 monomer units, possibly even less, and that the polyoxyethylene block M̄w = 3000 is just as capable of stabilizing the polystyrene particle as the higher molecular weight blocks. A very important factor was found to be the weight ratio of the two blocks: block copolymers with a polyoxyethylene content between 75 and 90 wt % were effective stabilizers for the emulsion polymerization of styrene © 1992 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1992.080300915
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  • 3
    Electronic Resource
    Electronic Resource
    Influence of steric length in electrosteric surfactants on emulsion polymerization (1989)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 37 (1989), S. 1415-1422 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Four PPG Avanel Series S surfactants (sodium alkyl polyether sulfonates) with varying ethylene oxide content (n = 3, 7, 9, and 15) were used to investigate the influence of the steric length in this type of electrosteric stabilizers on emulsion polymerization. The polymerization studies employing potassium persulfate as an initiator with styrene, methyl methacrylate, and vinyl acetate monomers showed no apparent change in particle size, number of particles, and polymerization rate with the changing steric length of the surfactant. Steric influences were observed in the redox-initiated systems of styrene, butyl acrylate, and methyl methacrylate. Increasing the ethylene oxide unit content from three to nine units decreased the rate of polymerization, the particle size and number in the polystyrene latexes. Polymerizations with the acrylates displayed the same trend except that the polymerization rate reached a minimum value at nine ethylene oxide units and increased when the surfactant containing 15 ethylene oxide units was used.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1989.070370523
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  • 4
    Electronic Resource
    Electronic Resource
    Emulsion polymerization of methyl methacrylate using poly(methyl methacrylate-co-2-hydroxypropyl methacrylate)-graft-polyoxyethylene as the stabilizer (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 1423-1431 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This study involved the use of an amphipathic graft copolymer, poly(methyl methacrylate-co-2-hydroxypropyl methacrylate)-graft-polyoxyethylene, as a stabilizer in the emulsion polymerization of methyl methacrylate. The stabilizing effectiveness of this graft copolymer was studied as a function of its chemical structure. It was found that the stabilizing effectiveness of the graft copolymer was independent of the molecular weight of the backbone within the investigated range of 4 × 103 g/mol to 2 × 104 g/mol. In all cases, stable emulsion polymerizations of methyl methacrylate were observed. Effective stabilization also occurred when the graft moieties possessed a molecular weight of either 2 × 103 g/mol or 5 × 103 g/mol. However, the stabilizing effectiveness was found to be dependent on the amount of polyoxyethylene (POE) contained in the graft copolymer. In this case, graft copolymers possessing 67% by weight POE were poor stabilizers, but ones with 85% POE were very good stabilizers. Moreover, the graft copolymers were found to be superior stabilizers as compared to POE homopolymers.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070420527
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesis and characterization of poly(methyl methacrylate-co-2-hydroxypropyl methacrylate)-graft-polyoxyethylene (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 43 (1991), S. 1577-1583 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: This study involved the synthesis and characterization of an amphipathic graft copolymer, poly(methyl methacrylate-co-2-hydroxypropyl methacrylate)-graft-polyoxyethylene. This amphipathic graft copolymer was synthesized utilizing a “grafting-onto” technique in which α-hydroxy-ω-methoxypolyoxyethylene was reacted with prepolymerized poly(methyl methacrylate-co-glycidyl methacrylate). Proof of copolymer formation was illustrated using water solubility, GPC, FTIR spectroscopy, and 13C-NMR spectroscopy. In all cases, proof of copolymer formation is demonstrated unequivocally.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070430821
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  • 6
    Electronic Resource
    Electronic Resource
    Block copolymers obtained by free radical mechanism III. Synthesis in emulsion (1987)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 33 (1987), S. 727-737 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Block copolymers were synthesized by a sequential free radical polymerization method with the use of di-t-butyl-4,4′-azobis(4-cyanoperoxyvalerate) as the trifunctional initiator. The polymerizations were carried out in two stages. First, the poly(methyl methacrylate) and poly(butyl methacrylate) polymeric initiators were synthesized by activating, at room temperature, the perester groups of the initiator with tetraethylenepentamine. For the second stage, the reaction ingredients were pre-emulsified, then the azo groups of these polymeric initiators were activated thermally in the presence of either styrene or p-methylstyrene. It was found that the reaction in the emulsion particles followed bulk kinetics, although the average size of the particles was small, 50-100 nm.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1987.070330304
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  • 7
    Electronic Resource
    Electronic Resource
    Block copolymers obtained by free-radical mechanism. I. Methyl methacrylate and styrene (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 24 (1979), S. 2051-2070 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Block copolymers were synthesized using styrene and methyl methacrylate as the monomers and a multifunctional initiator, di-t-butyl 4,4′-azobis(4-cyanoperoxyvalerate). The unique feature of this sequential initiator is the fact that the formation of the free radicals can be achieved thermally and/or by a redox system at different stages. The polymerizations for the formation of the block copolymer were carried out in two stages. First, a polymeric initiator was synthesized, which was then used in the second stage to initiate the polymerization of the second monomer. Styrene and methyl methacrylate were used as the comonomers. Selective solvent fractionation was used for the separation of the block from the homopolymers. The separation technique was found to be efficient, giving pure block copolymers which could subsequently be characterized by GPC, NMR, IR, and EM techniques.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070240913
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  • 8
    Electronic Resource
    Electronic Resource
    Emulsion polymerization of chloroprene. II. Molecular weightsThis investigation was carried out under the sponsorship of the U. S. Army Signal Corps, under Contracts DA 36-039 SC 42660. (1956)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 19 (1956), S. 563-577 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The molecular weights of emulsion polychloroprenes, prepared at four different temperatures in the presence and absence of a suitable mercaptan chain-transfer agents, have been studied. The particular mercaptan used, a tertiary dodecyl type, was found to disappear at the relatively slow rate, which was first-order up to high conversions. This permitted the preparation of polymer having a relatively uniform intrinsic viscosity up to high conversions. However, under certain conditions, the crosslinking reaction was found to give rise to the usual peaks in the viscosity-conversion curves. These curves differed from those of other dienes studied, in that the heights of the maxima depended not only on polymerization temperature but also on the mercaptan charge. This anomaly could be accounted for by the possibility of more than one mechanism of crosslinking. The above behavior made it impossible to obtain a quantitative measures of the crosslinking rate. However, observations of the postpolymerization changes experienced by this polymer lead to the conclusion that it has a high crosslinking rate.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1956.120199316
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  • 9
    Electronic Resource
    Electronic Resource
    Crosslinking in isoprene polymerizationPresented at the 124th Meeting of the American Chemical Society, Division of Polymer Chemistry, Chicago, Ill., September, 1953. This investigation was carried out under the sponsorship of the Office of Synthetic Rubber, Reconstruction Finance Corporation, in connection with the U. S. Government Synthetic Rubber Program. (1955)
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 15 (1955), S. 167-182 
    Details
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A study has been carried out on the emulsion polymerization of isoprene in an attempt to evaluate the relative rate of the crosslinking reaction and its variation with temperature. From the relation between primary chain length and gel formation during polymerization, the following values were obtained for the relative crosslinking rate constant, i.e., ratio of the velocity constants of the crosslinking and propagation reactions. TextTemperature,°C.K = kx/kp603.4 × 10-5704.3 × 10-5805.2 × 10-5The above data lead to a calculated value for the difference in the activation energy between the crosslinking and the propagation reaction (Ex - Ep) of 5.0 kcal. From these data and the known value of the propagation rate constant, it is possible to calculate the following absolute rate expression for the crosslinking reaction itself: \documentclass{article}\pagestyle{empty}\begin{document}$$ k_x = 8.5 \times 10^6 \exp \{14,800/RT\} $$\end{document}It is noteworthy that the relative crosslinking rate in isoprene polymerization is only about one-sixth that found for butadiene (K = 2 × 10-4 at 60°C.) apparently owing largely to a higher steric factor. Hence longer chains are possible for polyisoprene before network formation leads to gelation. In the Mutual Recipe, the rate per particle for isoprene polymerization is about three times as fast as for butadiene, although it is still short of the rate found in the ideal low temperature systems.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1955.120157914
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  • 10
    Electronic Resource
    Electronic Resource
    The branching reaction. III. Polymeric transfer constants of vinyl acetate with styrene and methyl methacrylate (1963)
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A: General Papers 1 (1963), S. 3043-3065 
    Details
    ISSN: 0449-2951
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A study has been carried out to determine the polymeric transfer constants of poly(vinyl acetate), polystyrene, and poly(methyl methacrylate) in the polymerization of vinyl acetate, as well as the similar transfer constants of poly(vinyl acetate) in the polymerization of styrene and methyl methacrylate. As before, this was accomplished by polymerizing each monomer in the presence of varying amounts of the desired oligomer and separating the resulting polymers. The effect of oligomer endgroups was checked by using oligomers of different molecular weight (1000-5000). As found previously for styrene and methyl methacrylate, there was no noticeable effect of polymeric endgroups on transfer activity, hence the transfer constants found refer to the interior units in the chain. The values of the various transfer constants are given. As expected, the vinyl acetate radical showed a reactivity in hydrogen abstraction which was several orders of magnitude greater than that of the styrene radical, and at least one order of magnitude greater than that of methyl methacrylate. The absolute values of the activation energy for the transfer step were remarkably similar, the difference in transfer activity being largely due to the difference in activation energy of the propagation reaction, and also to steric considerations.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1963.100011004
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