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  • 1
    Electronic Resource
    Electronic Resource
    Emulsion copolymerization of azeotropic styrene-acrylonitrile monomer mixture in polystyrene seed latexes (1985)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 10 (1985), S. 391-402 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The azeotropic 80:20 styrene-acrylonitrile mixture was polymerized in 190nm- and 300nm-diameter monodisperse polystyrene seed latexes by batch, batch-with-equilibrium-swelling, and semi-continuous polymerization. Polystyrene seed latexes were used to determine the degree of grafting of the substrate as well as the styrene-acrylonitrile copolymer. The Arrhenius plot of log (polymerization rate) of the seeded batch copolymerizations with reciprocal temperature comprised two linear regions with a sharp inflection point at 65°C. Specific volume measurements showed that the Tg of the monomer-swollen styrene-acrylonitrile copolymer was also 65°C. The final latex comprised the original seed particles grown to a larger size and, in some cases, a new crop of particles formed during the polymerization. The critical factor determining the formation of new particles was the surface area of the seed latex: at or above 226 m2/dl, new particles were not formed; at or below 179 m2/dl, a new crop of particles was nucleated, the number increasing with decreasing surface area. The degree of grafting of the polystyrene seed substrate was greater for the smaller particle size seed latex, and increased exponentially with increasing seed surface area. The amount of grafted styrene-acrylonitrile copolymer determined the stability of the grafted particles in acetone, a good solvent for the copolymer. Dynamic mechanical spectroscopy showed that the continuous phase was either the polystyrene substrate (Tg 104°C) or the styrene-acrylonitrile copolymer phase (Tg 120°C) except where the degree of grafting was high, in which case, the Tg was intermediate between the two values. Electron microscopy of thin film sections stained with ruthenium tetroxide confirmed which phase was continuous and showed interpenetrating networks for those systems of intermediate Tg.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1985.020101985127
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  • 2
    Electronic Resource
    Electronic Resource
    Emulsion polymerization of vinyl acetate using a polymerizable surfactant. III. Mathematical model (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 1403-1415 
    Details
    ISSN: 0887-624X
    Keywords: emulsion polymerization, role of particle/water interface ; vinyl acetate, emulsion copolymerization ; copolymerization in emulsion, mathematical model ; mathematical model, vinyl acetate/reactive surfactant emulsion copolymerization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A mathematical model was developed to aid in the further understanding of the growth of latex particles in the emulsion polymerization of vinyl acctate using a polymerizable surfactant, sodium dodecyl allyl sulfosuccinate (TREM LF-40). The model incorporates the main features of the system observed experimentally: copolymerization in the aqueous phase, at the particle surface, and chain transfer to TREM LF-40. The reactions at the particle/water interface and, more specifically, the chain transfer to TREM LF-40 leading to a decrease in the average number of radicals per particle, was found to be the most significant mechanism for explaining the difference in kinetic results found for TREM LF-40 and its nonpolymerizable counterpart. The copolymerization of vinyl acetate with TREM LF-40 was also shown to slow the overall polymerization rate. However, the copolymerization alone was not sufficient to account for the decreased polymerization rates observed experimentally. A combination of copolymerization and chain transfer to TREM LF-40 was found to provide a good fit of the experimental results. © 1993 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1993.080310607
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  • 3
    Electronic Resource
    Electronic Resource
    Morphology and grafting reactions in core/shell latexes (1987)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 1219-1233 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The particle morphology and percent grafting were investigated as a function of the crosslink density of the seed latex in two systems of core/shell latexes of polybutadiene/polymethyl methacrylate (PB/PMMA) and styrene-butadiene rubber/polymethyl methacrylate (SBR/PMMA) prepared by seeded emulsion polymerization at 50°C. The thin layer chromatography/flame ionization detection (TLC/FID) technique was used to characterize the grafting efficiency of the core/shell latexes. The percent grafting of the shell polymer was found to decrease with increasing the crosslink density of the core material. The particle morphology and precent grafting were also investigated as a function of composition and structure of the core material in four core/shell latex systems: polybutadiene/styrene-acrylonitrile copolymer (PB/SAN), (styrene-butadiene) random copolymer/styrene acrylonitrile copolymer (S:B/SAN), polystyrene : polybutadiene/styrene-acrylonitrile copolymer (PS:PB/SAN) and Kraton/styrene-acrylonitrile copolymer (Kraton/SAN), which were prepared by direct emulsification for the seed followed by emulsion polymerization at 70°C for the shell polymer. Grafting and crosslinking of the core material were found to be competitive reactions depending on the microstructure of the seed latex.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1987.080250503
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  • 4
    Electronic Resource
    Electronic Resource
    Process parameters and their effect on grafting reactions in core/shell latexes (1987)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 1755-1767 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The grafting of methyl methacrylate (MMA) onto polybutadiene (PB) latexes prepared by seeded emulsion polymerization at 50°C was investigated as a function of: (a) initiator concentration used in the secondary polymerization, (b) monomer-to-polymer ratio, (c) the specific surface area of the seed latex, and (d) the degree of conversion. The thin layer chromatography/flame ionization detection (TLC/FID) technique was used to determine the proportion of graft copolymer in the core/shell latex, It was found that grafting PMMA onto PB depended upon the concentration of initiator, decreasing as the concentration was increased. The amount of grafting increased with increasing specific surface area of the seed latex, while the molecular weight of the acetone-soluble graft copolymer decreased. The amount of graft copolymer was found to decrease concurrently with increasing monomer-to-polymer ratio and degree of conversion. These results suggest a hydrogen abstraction mechanism in the formation of graft PB-PMMA through a chain transfer process.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1987.080250705
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  • 5
    Electronic Resource
    Electronic Resource
    Emulsion polymerization of vinyl acetate using a polymerizable surfactant. II. Polymerization mechanism (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 2631-2644 
    Details
    ISSN: 0887-624X
    Keywords: emulsion polymerization, vinyl acetate ; emulsion polymerization, polymerizable surfactant ; emulsion polymerization, latex characterization ; emulsion polymerization, competitive growth seeded polymerization ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The mechanism of growth of latex particles in the emulsion polymerization of vinyl acetate using a polymerizable surfactant, sodium dodecyl allyl sulfosuccinate (TREM LF-40; Henkel) was investigated. Both the aqueous phase and the particle/water interface were found to be loci for the copolymerization of TREM LF-40 with vinyl acetate. Competitive growth experiments using TREM LF-40 and its nonpolymerizable derivative were conducted to separate the effects of aqueous phase and particle surface. Particle size analysis of the seeded and unseeded polymerizations coupled with kinetic results suggested that the reactions at the particle/water interface are more important and that the particle size of the latexes is a key parameter controlling the polymerization rate through copolymerization and chain transfer to the polymerizable surfactant at the particle surface. A decrease in particle size lead to an increase in the amount of TREM LF-40 polymerized at the particle surface and to a decrease in polymerization rate. © 1992 John Wiley & Sons, Inc.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1992.080301217
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  • 6
    Electronic Resource
    Electronic Resource
    Preparation and morphological characterization of microscopic composite particles (1991)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 29 (1991), S. 857-867 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Monodisperse microscopic poly (methyl methacrylate)/polystyrene composite particles of 1-10 μm diameter were prepared by seeded emulsion polymerization of styrene in poly (methyl methacrylate) seed particles which were initially prepared by dispersion polymerization. The resulting composite particles were characterized by transmission and scanning electron microscopy. The unique morphology of the composite particles comprised three types of polystyrene domains embedded in a continuous poly (methyl methacrylate) matrix: the dispersed “internal” domains in the interior, the interconnected “subsurface” domains that from a crust beneath the surface, and the separated “surface” domains at the surface. In addition to thermodynamics and kinetics, the phase separation in composite particles is affected by polymerization mechanism. The complicated particle morphology found is attributed to the coexistence of bulk polymerization and emulsion polymerization (radical absorption and desorption) mechanisms. An explanation of the formation of the observed morphology is proposed. With varying poly (methyl methacrylate)/styrene ratio, the internal viscosity and the competition between the two polymerization mechanisms resulted in a series of interesting morphologies.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1991.080290610
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  • 7
    Electronic Resource
    Electronic Resource
    Emulsion polymerization of vinyl acetate using a polymerizable surfactant. I. Kinetic studies (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 30 (1992), S. 2619-2629 
    Details
    ISSN: 0887-624X
    Keywords: emulsion polymerization, vinyl acetate ; emulsion polymerization, polymerizable surfactant ; emulsion polymerization, kinetics ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A polymerizable surfactant, sodium dodecyl allyl sulfosuccinate (TREM LF-40; Henkel) and its nonpolymerizable counterpart were used in comparative studies of the emulsion polymerization of vinyl acetate. The conversion-time behavior differed for the two surfactants; the TREM LF-40 showed a decrease in the polymerization rate with increasing concentration while its hydrogenated derivative showed the opposite behavior, the rate increasing with increasing surfactant. Particle size analysis revealed a decreasing particle size with increasing surfactant concentration for both series of reactions. An explanation for the seemingly ambiguous results obtained for the polymerizable surfactant was sought by examining the reactivity of its vinyl group in copolymerization with vinyl acetate and its allylic group in a chain transfer reaction. The results suggest that both the copolymerization and chain transfer reactions can lead to the observed reduction in polymerization rate with increasing TREM LF-40 concentration. © 1992 John Wiley & Sons, Inc.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1992.080301216
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  • 8
    Electronic Resource
    Electronic Resource
    A polymer thin-film technique to study the micromorphology of core/shell latexes (1987)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 25 (1987), S. 2595-2603 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of poly(styrene)/poly(styrene-co-acrylonitrile) core-shell latexes were synthesized by seeded emulsion polymerization. The dried latex was dissolved in toluene and then cast on the surface of water to form a very thin film (60-90 nm). Phase separation in the thin film was studied by transmission electron microscopy (TEM). Electron micrographs of these thin films yielded fine structure and interesting morphology that was unattainable by ultramicrotoming of the corresponding compression-molded specimens. Glass transition temperatures and percent grafted polystyrene were correlated with the TEM results. As grafting increases, mixing of the two phases improves, with the resulting Tg value being between the two Tg's of poly(styrene) and poly(styrene-co-acrylonitrile).
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1987.080250924
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  • 9
    Electronic Resource
    Electronic Resource
    Preparation of ABS (acrylonitrile/butadiene/styrene) latexes using hydroperoxide redox initiators (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 41 (1990), S. 2463-2477 
    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: The 80/20 (w/w) azeotropic styrene/acrylonitrile mixture was copolymerized at 35, 50, and 70°C in crosslinked polybutadiene seed latexes of varying particle size (range 113-242 nm) using the t-butyl or cumene hydroperoxide/sodium formaldehyde sulfoxylate dihydrate/EDTA-chelated Fe+2 redox initiator. Other initiators used for comparison were: (1) ammonium persulfate at 70°C; (2) ammonium persulfate/sodium bisulfite redox initiator at 35 and 50°C; (3) oil-soluble, 2,2'-azobis(2,4-dimethylvaleronitrile) at 50°C. The following polymerization parameters were varied systematically: (1) polybutadiene seed latex particle size; (2) monomer/polymer swelling ratio; (3) polymerization temperature; (4) type and concentration of initiator; and (5) mode (and duration) of initiator addition. The following parameters were determined: (1) polymer yield (final conversion); (2) variation of conversion with time; (3) morphology of the latex particles; (4) amount of coagulum; and (5) fraction of styrene/acrylonitrile monomer mixture grafted to the polybutadiene seed latex (defined here as grafting efficiency). For polymerizations using the t-butyl or cumene hydroperoxide/sodium formaldehyde sulfoxylate dihydrate/EDTA-chelated Fe+2 redox initiator, the rates of polymerization were faster, the grafting efficiencies were greater, and the amounts of coagulum were greater at 70°C than at 50 or 35°C. The rates of polymerization were decreased by decreasing the concentration of redox initiator or adding it incrementally. A 1.00/1.00/0.08 (w/w) t-butyl or cumene hydroperoxide/sodium formaldehyde sulfoxylate dihydrate/EDTA-chelated Fe+2 ratio gave reasonable polymerization rates at 35 and 50°C, and a 0.48/1.00/0.07 ratio, at 70°C. The latexes were stabilized during polymerization with 3% (based on seed solids) nonionic Igepal CO-990 at 35°C, and 6% at 50 and 70°C. The grafting efficiency increased with decreasing particle size of the polybutadiene seed latex and decreasing monomer/polymer ratio. The rate of polymerization increased with decreasing monomer/polymer ratio. The monomer/polymer ratio also affected the morphology of the particles; higher values gave inclusions of poly(styrene-co-acrylonitrile) in the polybutadiene particles. There were no significant differences in polymerization kinetics or grafting efficiency between the t-butyl and cumene hydroperoxides.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070410945
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  • 10
    Electronic Resource
    Electronic Resource
    Evaluation of alkylated diphenyl ether disulfonate surfactants in 60 : 40 styrene - butadiene emulsion copolymerization (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 41 (1990), S. 1549-1568 
    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: Dowfax* 2A1 is a branched C12-alkylated diphenyl ether disulfonate surfactant widely used in industrial emulsion polymerization because of its electrolyte tolerance, stability in concentrated acids and alkalis, oxidation resistance, temperature stability, efficiency in solubilization, and moderate foaming. This surfactant and other similar surfactants were evaluated as emulsifiers in 60 : 40 styrene-butadiene emulsion copolymerizations carried out at 70°C using persulfate ion initiator, and their solution properties were determined. The similar surfactants were Dowfax 3B2 (linear C10-alkylated), XD-8390 (linear C16), XD-8292 (linear C6), XD-8174 (linear C12), and various laboratory monoalkylated and dialkylated variations. Sodium lauryl sulfate, Aerosol MA, and Aerosol OT were used as standards for comparison. The emulsifier concentration required to give a 200-nm particle diameter varied strongly with the degree of alkylation of the emulsifier; the linear C16-monoalkylated diphenyl ether disulfonate emulsifier gave the desired diameter with the lowest concentration. The adsorption isotherms of these emulsifiers on the 60 : 40 styrene - butadiene copolymer particles were determined and correlated with the emulsifier structure. The interfacial tensions between styrene and the aqueous emulsifier solutions were measured and used to calculate the free energies of micellization and adsorption.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070410716
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