Monte Carlo simulation of micelle formation in mixed surfactants and palm-kernel oil esters-based nanoemulsion
For several years, the experimental laboratory and Molecular Dynamics (MD) simulation works was used to determine the behaviour and structural properties of nanoemulsions. In order to solve the problems related to transdermal drug nano-delivery system, the palm-kernel oil esters (PKOEs) nanoem...
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| Format: | Thesis |
| Language: | English |
| Published: |
2014
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| Subjects: | |
| Online Access: | http://psasir.upm.edu.my/id/eprint/71184/1/FS%202015%2065%20IR.pdf http://psasir.upm.edu.my/id/eprint/71184/ |
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| Summary: | For several years, the experimental laboratory and Molecular Dynamics (MD)
simulation works was used to determine the behaviour and structural properties of
nanoemulsions. In order to solve the problems related to transdermal drug nano-delivery
system, the palm-kernel oil esters (PKOEs) nanoemulsion can act as chemical
penetration enhancers with the help of non-ionic surfactants properties. Here, the
stochastic numerical methods or Monte Carlo (MC) was suggested to develop new
configurations of a system of interest. The physical properties of the mixed surfactants
and nanoemulsions formulation were studied using the Metropolis Monte Carlo (MMC)
algorithm while grand canonical Monte Carlo (GCMC) simulation was applied to
investigate the displacements of critical micelle concentration (CMC) for both systems.
Seven set of mixed surfactants (Brij 92, Brij 96 and water) models and five simulation
sets of PKOEs nanoemulsion (PKOEs, Brij 92, Brij 96, isopropanol as co-surfactant and
water) which were adapted from the experimental phase diagram was simulated using
MMC algorithm up to 10 and 20 million MC steps, respectively in order to determine
the most suitable composition of mixed surfactants and PKOEs nanoemulsion with
water molecules.The chemical potential for both model systems were calculated using Reference
Interaction Site Model (RISM) module. The most suitable composition from MMC
simulations was then grouped to five systems of mixed surfactants and six systems for
PKOEs nanoemulsion with a series of different values of temperature and chemical
potential resulted from the histogram-reweighting. The latest model systems were used
to simulate in grand canonical ensemble for 10 million MC steps with 50% of insertion
and removal of molecules and 50% of reptation moves. From the results, the acceptance
ratio for single atom moves of the mixed surfactants was increased as the percentage of
surfactants was increased from 0.429 to 0.591 meanwhile the acceptance ratio for single
atom moves for PKOEs nanoemulsion was decreased as the number of molecules
increased from 0.600 to 0.587 due to the different composition of the surfactants and
PKOEs nanoemulsion with water molecules where both systems formed spherical shape.
The physical properties of models such as radius of gyration, solvent accessible surface
area, radial distribution function and total energy were also determined. The chemical
potential for the mixed surfactants was produced at the range of 0.77 - 2.06 J/mol while
for the PKOEs nanoemulsion the value was ranged from 3.17 - 5.00 J/mol. The
displacement of CMC was increased while the insertion and deletion ratio movement
were decreased as the temperature and chemical potential increased due to the drop of
density in the cubic box during the simulation. Therefore these observations indicated
that the physical properties of mixed surfactant and PKOEs nanoemulsion systems were
adequately described by the simulation. The acceptance ratio for displacement
movement critical micelle concentration (CMC) for the mixed surfactants and PKOEs
nanoemulsion systems was also considered accepted with reasonable values produced. |
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