4 research outputs found
Mesoscopic Simulations of Adsorption and Association of PEO-PPO-PEO Triblock Copolymers on a Hydrophobic Surface: From Mushroom Hemisphere to Rectangle Brush
The dissipative particle dynamics
(DPD) method is used to investigate the adsorption behavior of PEO-PPO-PEO
triblock copolymers at the liquid/solid interface. The effect of molecular
architecture on the self-assembled monolayer adsorption of PEO-PPO-PEO
triblock copolymers on hydrophobic surfaces is elucidated by the adsorption
process, film properties, and adsorption morphologies. The adsorption
thicknesses on hydrophobic surfaces and the diffusion coefficient
as well as the aggregation number of Pluronic copolymers in aqueous
solution observed in our simulations agree well with previous experimental
and numerical observations. The radial distribution function revealed
that the ability of self-assembly on hydrophobic surfaces is P123 >
P84 > L64 > P105 > F127, which increased with the EO ratio
of the Pluronic copolymers. Moreover, the shape parameter and the
degree of anisotropy increase with increasing molecular weight and
mole ratio of PO of the Pluronic copolymers. Depending on the conformation
of different Pluronic copolymers, the morphology transition of three
regimes on hydrophobic surfaces is present: mushroom or hemisphere,
progressively semiellipsoid, and rectangle brush regimes induced by
decreasing molecular weight and mole ratio of EO of Pluronic copolymers
Mesoscopic Simulations of Adsorption and Association of PEO-PPO-PEO Triblock Copolymers on a Hydrophobic Surface: From Mushroom Hemisphere to Rectangle Brush
The dissipative particle dynamics
(DPD) method is used to investigate the adsorption behavior of PEO-PPO-PEO
triblock copolymers at the liquid/solid interface. The effect of molecular
architecture on the self-assembled monolayer adsorption of PEO-PPO-PEO
triblock copolymers on hydrophobic surfaces is elucidated by the adsorption
process, film properties, and adsorption morphologies. The adsorption
thicknesses on hydrophobic surfaces and the diffusion coefficient
as well as the aggregation number of Pluronic copolymers in aqueous
solution observed in our simulations agree well with previous experimental
and numerical observations. The radial distribution function revealed
that the ability of self-assembly on hydrophobic surfaces is P123 >
P84 > L64 > P105 > F127, which increased with the EO ratio
of the Pluronic copolymers. Moreover, the shape parameter and the
degree of anisotropy increase with increasing molecular weight and
mole ratio of PO of the Pluronic copolymers. Depending on the conformation
of different Pluronic copolymers, the morphology transition of three
regimes on hydrophobic surfaces is present: mushroom or hemisphere,
progressively semiellipsoid, and rectangle brush regimes induced by
decreasing molecular weight and mole ratio of EO of Pluronic copolymers
Mesoscopic Simulations of Adsorption and Association of PEO-PPO-PEO Triblock Copolymers on a Hydrophobic Surface: From Mushroom Hemisphere to Rectangle Brush
The dissipative particle dynamics
(DPD) method is used to investigate the adsorption behavior of PEO-PPO-PEO
triblock copolymers at the liquid/solid interface. The effect of molecular
architecture on the self-assembled monolayer adsorption of PEO-PPO-PEO
triblock copolymers on hydrophobic surfaces is elucidated by the adsorption
process, film properties, and adsorption morphologies. The adsorption
thicknesses on hydrophobic surfaces and the diffusion coefficient
as well as the aggregation number of Pluronic copolymers in aqueous
solution observed in our simulations agree well with previous experimental
and numerical observations. The radial distribution function revealed
that the ability of self-assembly on hydrophobic surfaces is P123 >
P84 > L64 > P105 > F127, which increased with the EO ratio
of the Pluronic copolymers. Moreover, the shape parameter and the
degree of anisotropy increase with increasing molecular weight and
mole ratio of PO of the Pluronic copolymers. Depending on the conformation
of different Pluronic copolymers, the morphology transition of three
regimes on hydrophobic surfaces is present: mushroom or hemisphere,
progressively semiellipsoid, and rectangle brush regimes induced by
decreasing molecular weight and mole ratio of EO of Pluronic copolymers
Dissipative Particle Dynamics Study on the Aggregation Behavior of Asphaltenes under Shear Fields
In
the present work, the effects of shear fields on the aggregation
of asphaltene molecules in heptane were investigated by means of dissipative
particle dynamics simulations. The geometries of asphaltene aggregates
without shear fields were studied, and the simulation results provide
an interpretation of the experimental results on the microscopic level.
The effects of shear fields on asphaltene aggregates were also investigated
by accessing the radial distribution functions, spatial orientation
correlation functions, and the radii of gyrations. We show that the
shear fields can destroy the conformational order of the aggregates
by damaging the organized structure and isolating the asphaltenes.
As the radius of gyration results show, the asphaltene molecules are
elongated to be alike-polymers by shear fields. Moreover, the reason
why the viscosity decreases under shear fields is that the shear fields
lead to the increase of dimerization free energies