Rupture of anomalous composite particles prepared by seeded emulsion polymerization in aging period

Okubo, Masayoshi; Katsuta, Yoshio; Matsumoto, Takuya

doi:10.1002/pol.1980.130180704

Cited by 154 publications

(85 citation statements)

References 6 publications

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“…Figure 1 a gives an overview of different particle morphologies [4][5][6] e. g. coreshell, hemispheres, raspberry-or confetti-like particles obtained by emulsion polymerization. The structure of these particles depends on the choice of the monomers, the synthesis parameters such as temperature, kind of initiator and surfactant, crosslinking density and many more variables [7][8][9][10]. The role of the interfacial tension in particle morphology was also examined [11,12].…”

Section: Introductionmentioning

confidence: 99%

Characterization of interphases in core—shell latexes by solid-state NMR

Landfester¹,

Spieß

1998

Acta Polym.

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Concepts for the characterization of composite latex particles by advanced solid‐state NMR methods are discussed. The techniques are based on 1H spin‐diffusion experiments usually applied to detect heterogeneities in polymers and polymer blends. In latexes, they allow one to characterize the morphology, including substructures in the interphase between core and shell. Motional heterogeneities within the phases are also detected. The techniques are used to characterize an extended series of core—shell particles composed of poly(n‐butyl acrylate) (PBuA) and poly(methyl methacrylate) (PMMA) synthesized in semicontinuous two‐step emulsion polymerization processes. The influence of process parameters such as synthesis temperature, crosslinking density in the core, shell content, particle size, and annealing are investigated.

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Section: Introductionmentioning

confidence: 99%

Characterization of interphases in core—shell latexes by solid-state NMR

Landfester¹,

Spieß

1998

Acta Polym.

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“…For example, Song et al had reported similar observations for the alcoholic dispersion polymerization of styrene using the same DVB cross-linker. [40][41][42] Therefore the one-shot batch formulation was repeated in the absence of any cross-linker (see entry 8, Table 1). DLS studies reported an intensity-average diameter of 430 nm for the resulting linear latex, while SEM indicated the formation of welldefined spherical particles, see Figure 2b.…”

Section: Latex Preparation and Characterizationmentioning

confidence: 99%

Novel Pickering Emulsifiers Based on pH-Responsive Poly(2-(diethylamino)ethyl methacrylate) Latexes

et al. 2013

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Emulsion copolymerization of 2-(tert-butylamino)ethyl methacrylate in the presence of divinylbenzene (DVB) cross-linker and monomethoxy-capped poly(ethylene glycol) methacrylate (PEGMA) macromonomer at 70 °C afforded sterically-stabilized latexes at approximately 10% solids at pH 9. Dynamic light scattering (DLS) and scanning electron microscopy (SEM) confirmed that relatively narrow size distributions were obtained. SEM confirmed the formation of spherical particles in the absence of any DVB cross-linker using a simple batch protocol, but in the presence of DVB it was necessary to use seeded emulsion polymerization under monomer-starved conditions to prevent the formation of latexes with ill-defined non-spherical morphologies. Lightly cross-linked latexes acquired cationic microgel character upon lowering the solution pH, as expected. Increasing the degree of cross-linking led to a progressively lower effective pK a of the copolymer chains from 8.0 to 7.3, which implies a gradual reduction in their basicity. Poly(tert-butylamino)ethyl methacrylate latex proved to be an effective Pickering emulsifier at pH 10, forming stable oilin-water emulsions when homogenized with either n-dodecane or sunflower oil at 12 000 rpm for 2 min. These Pickering emulsions exhibited pH-responsive behavior: lowering the solution pH to pH 3 resulted in immediate demulsification due to spontaneous desorption of the cationic microgels from the oil/water interface. With subsequent rehomogenization at high pH, four successive demulsification/emulsification pH cycles could be achieved without discernible loss in performance. However, no demulsification occurred on acidification of the fifth cycle.

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“…Figure 6 shows DMA curves of films prepared from batch polymerized copolymer latexes having S/Bu/MAA ratios similar to that of the second stage polymer in the two-phase latexes (R1 and R10). Two transitions are evident for both samples, with peaks in the tan 6 curves at 0 and 23°C for R1 and at 6 and 24°C for R10, which indicates that two different polymer phases were present in the samples.…”

Section: E+7mentioning

confidence: 93%

Viscoelastic properties and film morphology of heterogeneous styrene-butadiene latexes

Hagen¹,

Salmén²,

Karlsson³

et al. 1996

J. Appl. Polym. Sci.

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SYNOPSISHeterogeneous carboxylated styrene-butadiene (S/Bu) latexes were prepared by a twostage emulsion polymerization process, using three PS seeds with different molecular weights. The second-stage polymer was a copolymer with a fixed S/Bu ratio of 1 : 1 and a methacrylic acid (MAA) content of either 1 or 10 wt %. Morphological studies by transmission electron microscopy (TEM) as well as studies of the viscoelastic properties by mechanical spectroscopy have been performed on films prepared from the latexes. The studies showed that the glass transition temperature, Tg, of the second-stage polymer was considerably affected by copolymerization with MAA. An increase in the MAA content in the second-stage polymer increased the T, of this phase significantly. Addition of DVB as a crosslinking agent in the preparation of the PS seed phase substantially increased the rubbery moduli of the films, whereas the glass transition temperature of the second-stage polymer was unaffected. On the other hand, the presence of a chain transfer agent reduced the glass transition of the second-stage copolymer containing 1 w t % MAA dramatically, whereas the rubbery modulus was unaffected. When the MAA content was increased to 10 wt % the influence of the MAA monomer had a dominating effect on Te Latexes containing 10 wt % MAA had Tc values close to each other, regardless of chain transfer agent present in the second-stage polymerization. It was found that the morphology of the latex particles influenced the rubbery modulus of the films. The presence of irregularly shaped seed particles in samples prepared from a crosslinked PS seed had a considerable reinforcing effect on the films, whereas spherical seed particles originating from core-shell particles had a less reinforcing effect.

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Rupture of anomalous composite particles prepared by seeded emulsion polymerization in aging period

Cited by 154 publications

References 6 publications

Characterization of interphases in core—shell latexes by solid-state NMR

Characterization of interphases in core—shell latexes by solid-state NMR

Novel Pickering Emulsifiers Based on pH-Responsive Poly(2-(diethylamino)ethyl methacrylate) Latexes

Viscoelastic properties and film morphology of heterogeneous styrene-butadiene latexes

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