A new route to the formation of colloidal

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

Motivation: Segre et al PRL 86 (2001)

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

Phase Diagram for Square Well (3%) Isodiffusivity lines Repulsive Glass Percolation Line Spinodal AHS (Miller&Frenkel) Liquid+Gas A 3 Attractive Glass

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

ADD HERE SOME THING DISNMORE • AND POON. . .

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

How do clusters interact ?

Molecular Dynamics Data for Repulsive Yukawa Potential Several number densities n

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 ?

The T-dependence of S(q) =0. 15

T-dependence of the cluster size distribution

Dynamics. . . Collective Density autocorrelation function

T=0. 15 T=0. 10

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

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