1. Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation
Edward G. Timoshenko (*), Ronan Connolly and Yuri A. Kuznetsov
Theory and Computation Group, Department of Chemistry,
University College Dublin
Web page:
17-23 June 2004
Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

2. Statistical Mechanical approach
17-23 June 2004
Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

3. Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation
Techniques adopted
Metropolis Monte Carlo simulation in continuous space
Gaussian self-consistent (GSC) method
Equilibrium
17-23 June 2004
Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

4. Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation
GSC for kinetics
17-23 June 2004
Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

5. Self-consistent equation
Advantages: fairly simple, fast, qualitatively good for a wide
range of systems across varied solvent conditions.
Disadvantages: restricts the radial distribution functions to a
Gaussian shape. This leads to overestimation of swelling in
a good solvent and underestimation of energy in a poor one.
More recently: non-Gaussian (SGSC) generalisation obtained.
17-23 June 2004
Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

6. Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation
Branched polymers
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Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

7. Tomalia’s poly(amidoamine) PAMAM
All of these syntheses have been “divergent”, i.e., they involve the attachment of monomers to increasingly large dendrimers:
17-23 June 2004
Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

8. Fréchet’s convergent synthesis of poly(aryl ether) dendrimers
A number of more advanced (accelerated) synthesis
techniques have been also proposed recently.
17-23 June 2004
Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

9. Applications of dendrimers and stars
Useful properties:
1. Monodispersity
2. Large number of end-groups that can be functionalised
3. Relatively well-defined structures
4. Reduced viscosity and hydrodynamic radius.
Examples of applications:
1. Catalysis
2. Supramolecular chemistry
3. Medicine (e.g. drug delivery)
4. Coatings and rheology modifiers
5. Nanotechnology
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Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

10. Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation
Model
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Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

11. Nomenclature used for dendrimers
D2G2
D = number of monomers
before a branch point
G = number of “generations”
of branching
D1G1
D1G3
D1G5
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Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

12. Homo-dendrimers in good solvent
D3G7 is more spherical than D3G3
D3G7 has a hollow region near its centre
D3G3
D3G7
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Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

13. Scaling results for homo-dendrimers
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Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

14. Asphericity: Eigenvalues of shape tensor
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Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

15. Coil to globule transition
Gaussian Self-Consistent (GSC) results
Low U(0) - good solvent
High U(0)- poor solvent
Collapse transition is more pronounced for larger dendrimers
Poor Solvent
compact globules
Connectivity is not as important
Uniform density and no cavity
D4G5
D6G5
D3G5
D2G5
D1G5
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Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

16. Amphiphilic co-dendrimers
Inner-H D3G4
Outer-H D3G4
Both Inner- and Outer-H dendrimers form micellar structures
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Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

17. Inner-H co-dendrimers
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Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

18. Outer-H co-dendrimers
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Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

19. Binary core co-dendrimers
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Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

20. Our computing facilities
Web:
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Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

21. Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation
Acknowledgements
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Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

22. Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation
Screensaver
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Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation