3 research outputs found
Microcapsules Fabricated from Liquid Marbles Stabilized with Latex Particles
Millimeter-
and centimeter-sized “liquid marbles”
were readily prepared by rolling water droplets on a powder bed of
dried submicrometer-sized polystyrene latex particles carrying polyÂ[2-(diethylamino)Âethyl
methacrylate] hairs (PDEA-PS). Scanning electron microscopy studies indicated that flocs of the
PDEA-PS particles were adsorbed at the surface of these water droplets,
leading to stable spherical liquid marbles. The liquid marbles were
deformed as a result of water evaporation to adopt a deflated spherical
geometry, and the rate of water evaporation decreased with increasing
atmospheric relative humidity. Conversely, liquid marbles formed using
saturated aqueous LiCl solution led to atmospheric water absorption
by the liquid marbles and a consequent mass increase. The liquid marbles
can be transformed into polymeric capsules containing water by exposure
to solvent vapor: the PDEA-PS particles were plasticized with the
solvent vapor to form a polymer film at the air–water interface
of the liquid marbles. The polymeric capsules with aqueous volumes
of 250 ÎĽL or less kept their oblate ellipsoid/near spherical
shape even after complete water evaporation, which confirmed that
a rigid polymeric capsule was successfully formed. Both the rate of
water evaporation from the pure water liquid marbles and the rate
of water adsorption into the aqueous LiCl liquid marbles were reduced
with an increase of solvent vapor treatment time. This suggests that
the number and size of pores within the polymer particles/flocs on
the liquid marble surface decreased due to film formation during exposure
to organic solvent vapor. In addition, organic–inorganic composite
capsules and colloidal crystal capsules were fabricated from liquid
marbles containing aqueous SiO<sub>2</sub> dispersions
Microcapsules Fabricated from Liquid Marbles Stabilized with Latex Particles
Millimeter-
and centimeter-sized “liquid marbles”
were readily prepared by rolling water droplets on a powder bed of
dried submicrometer-sized polystyrene latex particles carrying polyÂ[2-(diethylamino)Âethyl
methacrylate] hairs (PDEA-PS). Scanning electron microscopy studies indicated that flocs of the
PDEA-PS particles were adsorbed at the surface of these water droplets,
leading to stable spherical liquid marbles. The liquid marbles were
deformed as a result of water evaporation to adopt a deflated spherical
geometry, and the rate of water evaporation decreased with increasing
atmospheric relative humidity. Conversely, liquid marbles formed using
saturated aqueous LiCl solution led to atmospheric water absorption
by the liquid marbles and a consequent mass increase. The liquid marbles
can be transformed into polymeric capsules containing water by exposure
to solvent vapor: the PDEA-PS particles were plasticized with the
solvent vapor to form a polymer film at the air–water interface
of the liquid marbles. The polymeric capsules with aqueous volumes
of 250 ÎĽL or less kept their oblate ellipsoid/near spherical
shape even after complete water evaporation, which confirmed that
a rigid polymeric capsule was successfully formed. Both the rate of
water evaporation from the pure water liquid marbles and the rate
of water adsorption into the aqueous LiCl liquid marbles were reduced
with an increase of solvent vapor treatment time. This suggests that
the number and size of pores within the polymer particles/flocs on
the liquid marble surface decreased due to film formation during exposure
to organic solvent vapor. In addition, organic–inorganic composite
capsules and colloidal crystal capsules were fabricated from liquid
marbles containing aqueous SiO<sub>2</sub> dispersions
pH-Responsive Hairy Particles Synthesized by Dispersion Polymerization with a Macroinitiator as an Inistab and Their Use as a Gas-Sensitive Liquid Marble Stabilizer
We studied dispersion polymerization in detail using <i>well-defined</i> pH-responsive polyÂ[2-(diethylamino)Âethyl methacrylate]-
(PDEA-) based macroinitiators as an inistab (<i>ini</i>tiator
+ <i>stab</i>ilizer). Colloidally stable polystyrene (PS)
latex particles carrying pH-responsive PDEA hair (PDEA–PS particles)
were successfully synthesized in polymerization media with solubility
parameters ranging between 22.3 (MPa)<sup>1/2</sup> and 26.0 (MPa)<sup>1/2</sup>. The number-average particle diameters were finely controlled
between 90 and 460 nm. The PDEA–PS latex particles were dispersed
in acidic aqueous media in which the PDEA hair was protonated and
solvated, and were flocculated in basic aqueous media in which the
PDEA hair was deprotonated and precipitated. The dried PDEA–PS
particles served as an effective gas-responsive stabilizer for liquid
marbles. The liquid marbles were stable in H<sub>2</sub>O vapor for
over 18 h, but disintegrated immediately (<2 s) upon exposure to
HCl gas