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20231223053515.0 |
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231223s2004 xx ||||| 00| ||eng c |
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|a pubmed24n0501.xml
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|a (DE-627)NLM150267819
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|a (NLM)15350114
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|a DE-627
|b ger
|c DE-627
|e rakwb
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|a eng
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| 100 |
1 |
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|a Simovic, Spomenka
|e verfasserin
|4 aut
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| 245 |
1 |
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|a Nanoparticles of varying hydrophobicity at the emulsion droplet-water interface
|b adsorption and coalescence stability
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| 264 |
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|c 2004
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|a Text
|b txt
|2 rdacontent
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|a ohne Hilfsmittel zu benutzen
|b n
|2 rdamedia
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| 338 |
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|a Band
|b nc
|2 rdacarrier
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|a Date Completed 13.06.2006
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|a Date Revised 21.11.2013
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|a published: Print
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|a Citation Status MEDLINE
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|a The coalescence stability of poly(dimethylsiloxane) emulsion droplets in the presence of silica nanoparticles ( approximately 50 nm) of varying contact angles has been investigated. Nanoparticle adsorption isotherms were determined by depletion from solution. The coalescence kinetics (determined under coagulation conditions at high salt concentration) and the physical structure of coalesced droplets were determined from optical microscopy. Fully hydrated silica nanoparticles adsorb with low affinity, reaching a maximum surface coverage that corresponds to a close packed monolayer, based on the effective particle radius and controlled by the salt concentration. Adsorbed layers of hydrophilic nanoparticles introduce a barrier to coalescence of approximately 1 kT, only slightly reduce the coalescence kinetics, and form kinetically unstable networks at high salt concentrations. Chemically hydrophobized silica nanoparticles, over a wide range of contact angles (25 to >90 degrees ), adsorb at the droplet interface with high affinity and to coverages equivalent to close-packed multilayers. Adsorption isotherms are independent of the contact angle, suggesting that hydrophobic attraction overcomes electrostatic repulsion in all cases. The highly structured and rigid adsorbed layers significantly reduce coalescence kinetics: at or above monolayer surface coverage, stable flocculated networks of droplets form and, regardless of their wettability, particles are not detached from the interface during coalescence. At sub-monolayer nanoparticle coverages, limited coalescence is observed and interfacial saturation restricts the droplet size increase. When the nanoparticle interfacial coverage is >0.7 and <1.0, mesophase-like microstructures have been noted, the physical form and stability of which depends on the contact angle. Adsorbed nanoparticle layers at monolayer coverage and composed of a mixture of nanoparticles with different hydrophobisation levels form stable networks of droplets, whereas mixtures of hydrophobized and hydrophilic nanoparticles do not effectively stabilize emulsion droplets
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|a Journal Article
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|a Research Support, Non-U.S. Gov't
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7 |
|a Dimethylpolysiloxanes
|2 NLM
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| 650 |
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7 |
|a Emulsions
|2 NLM
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|a Silicones
|2 NLM
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|a Water
|2 NLM
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|a 059QF0KO0R
|2 NLM
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|a baysilon
|2 NLM
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|a 63148-62-9
|2 NLM
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| 650 |
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|a Silicon Dioxide
|2 NLM
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| 650 |
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|a 7631-86-9
|2 NLM
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| 700 |
1 |
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|a Prestidge, Clive A
|e verfasserin
|4 aut
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| 773 |
0 |
8 |
|i Enthalten in
|t Langmuir : the ACS journal of surfaces and colloids
|d 1992
|g 20(2004), 19 vom: 14. Sept., Seite 8357-65
|w (DE-627)NLM098181009
|x 1520-5827
|7 nnns
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| 773 |
1 |
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|g volume:20
|g year:2004
|g number:19
|g day:14
|g month:09
|g pages:8357-65
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|a AR
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|d 20
|j 2004
|e 19
|b 14
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|h 8357-65
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