modeling of hybrid materials
DESCRIPTION
Modeling of Hybrid Materials. Alessandro Patti Complex Systems Department of Chemical Engineering, URV Tarragona Supervisor: Flor R. Siperstein. Summary. Hybrid materials Monte Carlo simulations Aims of the project and applications Simulation method First results Next steps. - PowerPoint PPT PresentationTRANSCRIPT
Modeling of Hybrid Materials
Alessandro Patti
Complex SystemsDepartment of Chemical Engineering, URV
TarragonaSupervisor: Flor R. Siperstein
Alessandro Patti Modelling of Hybrid Materials
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Summary
1. Hybrid materials
2. Monte Carlo simulations
3. Aims of the project and applications
4. Simulation method
5. First results
6. Next steps
Key words: MC simulations, self-assembly, phase diagrams, mesoporous materials
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Hybrid materials
Surfactant
Micelle
Hydrophilic headHydrophobic tail
+Inorganic precursor
Organic-inorganicstructured materialOrganic-inorganicstructured material
Synthesis mechanisms:1. LC templating2. Ion exchange
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Mesoporous materials
Removal of the organic matter:mesoporous matrix
Pore size: 2 nm < d < 50 nm
Material properties:OpticalMechanicalChemical
Main applications {• Optics• Electronics• Membranes• Catalysis• Sensors
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Monte Carlo Simulations
Objective
Calculation of macroscopic properties from microscopic properties
Averaging Method
Ensemble Averages
NVT EnsembleNPT EnsemblemPT Ensemble
Generation of Random Configurations
Use of Random NumberImportance Sampling
Markov ChainMetropolis Algorithm
Approximations
Periodic Boundary ConditionMinimum Image Convention
Neighborhood List
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Monte Carlo SimulationsStart
Generate initial configuration
Calculate Energy
Trial MoveAcceptance Criteria
Calculate Summation of Properties
Average Properties End
LoopNcycles
Random Number Generator
PBC and MIC
Importance Sampling
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Aims of the project
determine the phase behavior of ordered mesoporous metal oxides using surfactants as structure directing agents
predict the material's final structure and the mechanism for the transformation of spherical micelles into ordered liquid crystals phases
determine the equilibrium of the surfactant-inorganic structures, the regions in the phase diagram where they are observed and the stability of different phases
This research project will try to:
model and understand at a molecular level the formation and properties of self-assembled hybrid materials
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Simulation method
3D lattice MC simulations in the N,V,T ensembleInorganic component: silica, 2 connected sites in the boxSurfactant: H4T4 - 8 connected sites in the lattice boxSolvent: water, empty sitesMoves: reptation, bias, partial regrowth
Effective interaction
jjiiijij 2
1
Coordination number: 26
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Results
Partial miscibility
L = 24*24*100T* = 8.0Nsurf = 1000Ninorg = 2000 N = 3•109
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Results – Phase diagrams
Partial miscibility
T* = 8.0
Ternary Plot
Surfactant0 10 20 30 40 50 60 70 80 90 100
Inorganic
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Solvent
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Conclusions
Monte Carlo simulations are used to study the formationand properties of self-assembled hybrid materials
A lattice model is used to represent the organic and the inorganic components
Phase separation and aggregation properties are studied interms of equilibrium and stability of the final structures
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Ternary Plot
Surfactant0 10 20 30 40 50 60 70 80 90 100
Inorganic
0
10
20
30
40
50
60
70
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90
100
Solvent
0
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Next steps
Immiscibility gap??
Its shape and
location
determine the
different liquid
crystal phases
that can be
formed
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References
• Phase Separation and Liquid Crystal Self-Assembly in Surfactant-Inorganic- Solvent Systems, Flor R. Siperstein and Keith E. Gubbins, Langmuir 2003, 19, 2049- 2057• Chemical Strategies To Design Textured Materials: from Microporous and Mesoporous Oxides to Nanonetworks and Hierarchical Structures, Galo J. de A. A. Soler-Illia, Clement Sanchez, Benedicte Lebeau and Joel Patarin, Chem. Rev. 2002, 102, 4093-4138• Ternary Oil-Water-Amphiphile Systems: Self-Assembly and Phase Equilibria S.Y. Kim, A. Z. Panagiotopoulos and M. A. Floriano, Molec. Phys., 100, 2213-20, 2002