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OKUBO, Masayoshi; TSUTSUMI, Yoshitaka; KADOOKA, Tsuneo; Matsumoto, Tsunetaka

doi:10.1295/koron.37.145

Cited by 5 publications

(4 citation statements)

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“…It may well be due to the surfactant-free nature of the nanocomposite syntheses, since the extent of water absorption for acrylic latex films prepared by surfactant-free copolymerization was reported to be as low as 15% by mass. 31 However, XPS studies (see below) suggest an alternative explanation. It is noteworthy that, after water absorption, the nanocomposite film prepared from JA7 remains almost transparent; minimal whitening is observed.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Characterization of Novel Film-Forming Vinyl Polymer/Silica Colloidal Nanocomposites

et al. 2001

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We report the surfactant-free synthesis of new, film-forming vinyl polymer/silica colloidal nanocomposites by copolymerization of 4-vinylpyridine (4VP) with either n-butyl acrylate (n-BuA) or n-butyl methacrylate (n-BuMA) in the presence of an ultrafine aqueous silica sol. Highly transparent, free-standing nanocomposite films were readily obtained by solution-casting from aqueous media at room temperature. Thermogravimetric analyses indicated silica contents ranging from 20% to 56%, depending on the nanocomposite formulation, and intensity-average particle diameters ranged from 139 to 305 nm. The influence of the synthesis conditions on the particle properties was also studied. Reducing the initial silica concentration at constant monomer concentration led to an increase in the particle size and reduced colloid stability, indicating that the ultrafine silica sol stabilized the colloidal nanocomposites. Colloidal nanocomposites were also prepared using a methacrylate-capped poly(ethylene glycol) (MPEGMA) macromonomer as a reactive steric stabilizer. The resulting sterically stabilized nanocomposites exhibited enhanced colloid stability, as expected. In addition, this polymeric stabilizer led to an increase in the silica content of the nanocomposites and lower minimum film-forming temperatures due to its plasticizing effect. ζ potential measurements indicated that the MPEGMA stabilizer was mainly located at the surface of the nanocomposite particles, as expected. 1 H NMR spectroscopy studies of the polymeric component extracted from selected nanocomposites confirmed the incorporation of both the 4VP and the film-forming comonomer (and also the MPEGMA macromonomer, where applicable). Transmission electron microscopy studies confirmed the presence of silica in the particles, and thin film cross-sections prepared by cryo-ultramicrotomy indicated that the surface of the nanocomposite particles was silica-rich, suggesting a core-shell morphology. However, X-ray photoelectron spectroscopy studies of the n-BuA-based nanocomposite films indicated that profound morphological changes occurred during film formation. The more hydrophobic copolymer component diffuses to the film/air interface and displaces the hydrophilic silica particles, leading to a surface excess of the copolymer component. This probably accounts for the relatively low water uptake by these nanocomposite films. LA010138A

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Section: Resultsmentioning

confidence: 99%

Synthesis and Characterization of Novel Film-Forming Vinyl Polymer/Silica Colloidal Nanocomposites

et al. 2001

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“…The variation in optical density of the blend emulsion film (20 × 25 mm) was recorded as a function of dipping time in water at 30°C with an incident wavelength of 610 nm. The portion in contact with water was limited to one side of the specimen, that is, the air‐side or release‐paper–side (bottom‐side) surface, as described in detail in a previous study 7…”

Section: Methodsmentioning

confidence: 99%

“…Compared to films containing emulsifier, films prepared from polymer emulsion produced by emulsifier‐free emulsion polymerization had high water resistance6 and good adhesion 1–3. On the other hand, a film cast from emulsifier‐free polymer emulsion having low colloidal stability had a porous structure resulting from the coagulation of particles during the drying process, and the porous film was characterized by lower water resistance than that of emulsifier‐containing emulsion films 7, 8. Such a porous emulsion film must have high water vapor permeability, which is needed for medical adhesive tape.…”

Section: Introductionmentioning

confidence: 99%

Preparation of two‐layer film having porous structure by emulsion blend technique

Okubo

Terada

Kagawa

2003

J of Applied Polymer Sci

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A two-layer film consisting of a tacky layer (air side) and a porous nontacky layer (release-paper side) was prepared by casting blend emulsion on a release paper, in which 150-nm 2-ethylhexyl acrylate-2-methoxyethyl acrylate-acrylic acid terpolymer particles having high storage stability and 542-nm ethyl acrylate-methyl methacrylate copolymer particles having low storage stability were dispersed. Both emulsion particles were produced by emulsifier-free emulsion copolymerizations. The difference of tackiness between both surfaces increased with increases in the film-formation time and the concentration of electrolytes in the blend emulsion, and resulted in the two-layer film. The film had a high water vapor permeability, which is also needed for medical adhesive tape.

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“…Therefore, during polymerization the phase separation of polymers occurs in the particles and polymer particles with different heterogeneous structures are formed at the end of the process according to the polymerization conditions. We are interested in this polymer mixing process in microparticles with diameters in the range 0.1-1 .O pm (1)(2)(3)(4)(5)(6)(7)(8) because the properties of films cast from such composite polymer emulsions were clearly varied corresponding to the morphology of particles, even if the polymer compositions are same (3,4,9). In addition, in those polymerizations we observed some anomalous particles, e.g., "ionfettilike" (2-S), "raspberrylike" (3-5,7), and "void" (8) particles.…”

Section: Introductionmentioning

confidence: 99%

Studies on suspension and emulsion. li. peculiar morphology of composite polymer particles produced by seeded emulsion polymerization

Okubo

Katsuta

Matsumoto

1982

J. Polym. Sci. B Polym. Lett. Ed.

100

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Cited by 5 publications

References 0 publications

Synthesis and Characterization of Novel Film-Forming Vinyl Polymer/Silica Colloidal Nanocomposites

Synthesis and Characterization of Novel Film-Forming Vinyl Polymer/Silica Colloidal Nanocomposites

Preparation of two‐layer film having porous structure by emulsion blend technique

Studies on suspension and emulsion. li. peculiar morphology of composite polymer particles produced by seeded emulsion polymerization

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