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A new route to the formation of colloidal gels

A new route to the formation of colloidal gels

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A new route to the formation of colloidal gels

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  1. A new route to the formation ofcolloidal gels • Playing with • Short Range Attractions and Long Range Repulsions • Stefano Mossa, Francesco Sciortino, Piero • Tartaglia, Emanuela Zaccarelli

  2. Motivation: Segre et al PRL 86 (2001)

  3. The quest for the ideal (thermoreversible) gel….model The quest 1) Long Living reversible bonds 2)No Phase Separation 3) No Crystallization Are 1 and 2 mutually exclusive ? Low Temperature Long Bond Lifetime Condensation

  4. Phase Diagram for Square Well (3%) Repulsive Glass Iso-diffusivity lines Percolation Line Spinodal AHS (Miller&Frenkel) A3 Attractive Glass Liquid+Gas

  5. How to stay at low T without condensation ? Reasons for condensation (Frank, Hill, Coniglio) Physical Clusters at low T if the infinite cluster is the lowest energy state How to make the surface more stable than the bulk ? The quest

  6. The case of an attractive potential Cluster Ground State for the 2n-n potential (Lekkerkerker)

  7. ADD HERE SOMETHINGDISNMORE • AND POON......

  8. How to make negative ? Upper Limit Optimal Size Groenewold and Kegel

  9. How do clusters interact ?

  10. Molecular Dynamics Data for Repulsive Yukawa Potential Several number densities n

  11. The Optimal Size Controls if the system is going to be a cluster phase or an arrested disordered state (Wigner Glass) Are the simulation data providing support for this picture ?

  12. The T-dependence of S(q) =0.15

  13. T-dependence of the cluster size distribution

  14. Dynamics... Collective Density autocorrelation function

  15. T=0.15 T=0.10

  16. A case in which clustering is.... home made ! Star Polymers low f high f

  17. Cluster Phase stabilized by the competition of Short-Ranged and Repulsive-Long-Ranged interactions The disordered arrest problem has been expressed in term of glass transition of cluster Colloidal Gels = Wigner Glasses