Photoconductive properties of cadmium sulfide encapsulated in polymers

Haga, Yutaka; Nakajima, Masahisa; Yosomiya, Ryûtoku

doi:10.1002/apmc.1987.051530105

Cited by 6 publications

(2 citation statements)

References 8 publications

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“…The encapsulation of inorganic particles of submicron size has been investigated using a number of different polymerization methods, including emulsion polymerization,7–22 interfacial polymerization,23–25 suspension polymerization,26–28 and more recently, miniemulsion polymerization 29. Inorganic particles have included TiO 2 , carbon black, magnetite, quartz powder, SiO 2 , CdS, BaSO 4 , and CaCO 3 , while polymers have included polystyrene, poly(vinyl acetate), poly(butyl acrylate), and poly(methyl methacrylate).…”

Section: Introductionmentioning

confidence: 99%

“…Inorganic particles have included TiO 2 , carbon black, magnetite, quartz powder, SiO 2 , CdS, BaSO 4 , and CaCO 3 , while polymers have included polystyrene, poly(vinyl acetate), poly(butyl acrylate), and poly(methyl methacrylate). Both conventional and emulsifier‐free emulsion polymerizations13–22 have been carried out. The major obstacles in successfully applying emulsion polymerization as an encapsulation method are attributed to the complexity of the particle nucleation mechanism (micellar, homogeneous) and the difficulties in controlling the dispersion stability of the inorganic particles in the aqueous phase prior to and during polymerization.…”

Section: Introductionmentioning

confidence: 99%

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Encapsulation of titanium dioxide in styrene/n‐butyl acrylate copolymer by miniemulsion polymerization

Al‐Ghamdi

Sudol

Dimonie

et al. 2006

J of Applied Polymer Sci

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Miniemulsion copolymerization of styrene/ n-butyl acrylate was investigated as a means of encapsulating hydrophilic titanium dioxide (TiO 2 ) in a film-forming polymer. Dispersion studies of the TiO 2 were first carried out to determine the choice of stabilizer, its concentration, and the dispersion process conditions for obtaining stable TiO 2 particles with minimum particle size. Through screening studies of various functional stabilizers and shelf-life stability studies at both room and polymerization temperatures, Solsperse 32,000 was selected to give relatively small and stable TiO 2 particles at 1 wt % stabilizer and with 20 -25 min sonification. The subsequent encapsulation of the dispersed TiO 2 particles in styrene/n-butyl acrylate copolymer (St/BA) via miniemulsion polymerization was carried out and compared with a control study using styrene monomer alone. The lattices resulting from the miniemulsion encapsulation polymerizations were characterized in terms of the encapsulation efficiencies (via density gradient column separations; DGC) and particle size (via dynamic light scattering). Encapsulation efficiencies revealed that complete encapsulation of all of the TiO 2 by all of the polymer was not achieved. The maximum encapsulation efficiencies were 79.1% TiO 2 inside 61.7% polystyrene and 63.6% TiO 2 inside 38.5% St/BA copolymer. As the density of the particles collected from the DGC increased from one layer to another, both the average particle size and the number of the TiO 2 particles contained in each latex particle increased.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Encapsulation of titanium dioxide in styrene/n‐butyl acrylate copolymer by miniemulsion polymerization

Al‐Ghamdi

Sudol

Dimonie

et al. 2006

J of Applied Polymer Sci

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Thermal behaviour of TiO₂‐encapsulating polymers

Haga

Watanabe

Yosomiya

et al. 1991

Angew. Makromol. Chem.

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Comparing the thermal properties of TiO, encapsulating polystyrene and poly(methy1 methacrylate) with those of TiO, dispersion polymers it was found that the encapsulating polymers have two thermal relaxation regions. The activation energy of those thermal relaxation regions was determined using the Wunderlich method and it was found that the values are similar to the activation energy for the dynamic dispersion. It is suggested that the low-temperature thermal relaxation is caused by the local change of conformation of molecular chains, while the high-temperature thermal relaxation is similar to that of the normal glass transition temperature including the interaction with TiO,. In addition, the thermal behaviour near the degradation point in different atmospheres indicates that the encapsulating polymer has a specific structure for adsorbing a large amount of oxygen. ZUSAMMENFASSUNGDie thermischen Eigenschaften von Polystyrol and Poly(methylmethacry1at) mit verkapseltem und dispergiertem TiO, wurden verglichen. Die verkapselnden Polymeren zeigen zwei thermische Relaxationsbereiche, deren nach Wunderlich ermittelte Aktivierungsenergien denen von dynamischen Dispersionen ahnlich sind. Es wird vorgeschlagen, da8 die Niedertemperaturrelaxation durch lokale hderungen der Konformation der Makromolekule hervorgerufen wird, wahrend die Hochtemperaturrelaxation dem normalen Glasubergang einschlieBlich der Wechselwirkung mit TiO, vergleichbar ist. Das thermische Verhalten nahe der Zersetzungstemperatur in verschiedenen Atmosphiiren deutet darauf hin, da8 in den verkapselnden Polymeren spezifische Strukturen vorhanden sind, die eine groBe Menge Sauerstoff adsorbieren konnen.

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Encapsulating polymerization of titanium dioxide

Haga

Watanabe

Yosomiya

1991

Angew. Makromol. Chem.

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Titanium dioxide was encapsulated in polymethyl methacrylate and polystyrene by the emulsion polymerization process, and the influence of various polymerization conditions such as the monomer and initiator concentrations and amounts of titanium oxide on the polymerization behavior was investigated. In the polymerization mixture where the end of the polymer chain and the metal oxide surface are oppositely charged, unextractable polymer is formed well. The encapsulating polymers show special structures with high molecular weight and high density. ZUSAMMENFASSUNGTitandioxid wurde durch Emulsionspolymerisation mit Polymethylmethacrylat und Polystyrol verkapselt. Der EinfluD der Monomer-, Initiator-und Ti0,-Konzentration und des pH-Wertes der Emulsion wurde untersucht. In den Emulsionen, in denen die Kettenenden und die MetalloxidoberflBche entgegengesetzt geladen sind, bildet sich nichtextrahierbares Polymeres. Die Kapselpolymeren haben ein hohes Molekulargewicht und eine hohe Dichte, was auf spezielle Strukturen der Polymeren hinweist. 0 1991 Hiithig & Wepf Verlag, Basel CCC 0003-3146/91/$03.00

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Photoconductive properties of cadmium sulfide encapsulated in polymers

Cited by 6 publications

References 8 publications

Encapsulation of titanium dioxide in styrene/n‐butyl acrylate copolymer by miniemulsion polymerization

Encapsulation of titanium dioxide in styrene/n‐butyl acrylate copolymer by miniemulsion polymerization

Thermal behaviour of TiO₂‐encapsulating polymers

Encapsulating polymerization of titanium dioxide

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Photoconductive properties of cadmium sulfide encapsulated in polymers

Cited by 6 publications

References 8 publications

Encapsulation of titanium dioxide in styrene/n‐butyl acrylate copolymer by miniemulsion polymerization

Encapsulation of titanium dioxide in styrene/n‐butyl acrylate copolymer by miniemulsion polymerization

Thermal behaviour of TiO2‐encapsulating polymers

Encapsulating polymerization of titanium dioxide

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Thermal behaviour of TiO₂‐encapsulating polymers