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: http://darkstar.ucd.ie E-mail: Edward.Timoshenko@ucd.ie 17-23 June 2004 Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

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

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

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

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

Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation Branched polymers 17-23 June 2004 Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

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

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

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 17-23 June 2004 Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation Model 17-23 June 2004 Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

Nomenclature used for dendrimers D2G2 D = number of monomers before a branch point G = number of “generations” of branching D1G1 D1G3 D1G5 17-23 June 2004 Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

Homo-dendrimers in good solvent D3G7 is more spherical than D3G3 D3G7 has a hollow region near its centre D3G3 D3G7 17-23 June 2004 Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

Scaling results for homo-dendrimers 17-23 June 2004 Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

Asphericity: Eigenvalues of shape tensor 17-23 June 2004 Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

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 17-23 June 2004 Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

Amphiphilic co-dendrimers Inner-H D3G4 Outer-H D3G4 Both Inner- and Outer-H dendrimers form micellar structures 17-23 June 2004 Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

Inner-H co-dendrimers 17-23 June 2004 Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

Outer-H co-dendrimers 17-23 June 2004 Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

Binary core co-dendrimers 17-23 June 2004 Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

Our computing facilities Web: http://darkstar.ucd.ie/cluster, http://chemistry.ucd.ie/cscb/cluster 17-23 June 2004 Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation Acknowledgements 17-23 June 2004 Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation

Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation Screensaver 17-23 June 2004 Shapes of Amphiphilic Co-dendrimers by Monte Carlo Simulation