Reverse microemulsions are thermodynamically stable ... · Reverse microemulsions are...
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0.1 1 4000 8000 12000 16000 20000 q [nm -1 ] Time [s] Reverse microemulsions are thermodynamically stable suspensions of water droplets in oil i.e. micelles that are stabilized by an interface surfactant. Water droplets are typically 1-50 nm in diameters. They can carry dissolved salt ions and exchange their content upon collisions, which lead to mineral precipitation. These droplets are believed to act as “nano-reactors” because precipitation occurs in the water pools shielded by the surfactants from the oil phase. We used this approach to follow the nucleation and growth of CaCO3 by mixing two distinct microemulsions containing Ca 2+ and CO3 2- ions. The as-precipitated primary particles of CaCO3 had a diameter of 6-7 nm, while the CaCO3 agglomerates had 100-200 nm . water + Ca 2+ water + CO 3 2- "oil" 6-7 nm Possible change of shape, electron density and/or polydispersity Agglomeration. Concerns only a small fraction of particles 0.00E+00 1.67E-07 6.69E-07 2.67E-06 4.01E-06 4.68E-06 5.68E-06 6.69E-06 7.36E-06 1.07E-05 1.34E-05 2.14E-05 3.21E-05 4.28E-05 Intensity [a.u.] 6-7 nm ~50 nm Precipitation of calcium carbonate amorphous nanoparticles in microemulsions followed by in situ and time-resolved small angle X-ray scattering. Two scattering contributions are clearly visible: (1) scattering from individual micelles at high-q and (2) scattering from agglomerates at low-q.
Transcript of Reverse microemulsions are thermodynamically stable ... · Reverse microemulsions are...
0.1 1
4000
8000
12000
16000
20000
q [nm-1]
Tim
e [s
]
0.00E+001.67E-076.69E-072.67E-064.01E-064.68E-065.68E-066.69E-067.36E-061.07E-051.34E-052.14E-053.21E-054.28E-05
Intensity [a.u.]
Reverse microemulsions are thermodynamically stable suspensions of water droplets in oil i.e. micelles that are stabilized by an interface surfactant. Water droplets are typically 1-50 nm in diameters. They can carry dissolved salt ions and exchange their content upon collisions, which lead to mineral precipitation. These droplets are believed to act as “nano-reactors” because precipitation occurs in the water pools shielded by the surfactants from the oil phase. We used this approach to follow the nucleation and growth of CaCO3 by mixing two distinct microemulsions containing Ca2+ and CO3
2-ions. The as-precipitated primary particles of CaCO3 had a diameter of 6-7 nm, while the CaCO3 agglomerates had 100-200 nm .
water + Ca2+
water + CO3
2-
"oil"
6-7 nm
Possible change of shape, electron density and/or
polydispersity
Agglomeration. Concerns only a small fraction of
particles
0.1 1
4000
8000
12000
16000
20000
q [nm-1]
Tim
e [s
]
0.00E+001.67E-076.69E-072.67E-064.01E-064.68E-065.68E-066.69E-067.36E-061.07E-051.34E-052.14E-053.21E-054.28E-05
Intensity [a.u.]
6-7 nm
~50 nm
P re c i p i t a t i o n o f c a l c i u m c a r b o n a t e amorphous nanoparticles in microemulsions followed by in situ and time-resolved small angle X-ray scattering. Two scattering contributions are clearly visible: (1) scattering from individual micelles at high-q and (2) scattering from agglomerates at low-q.
