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SUMMARY:Liquid Crystal and Nonequilibrium states in mixed suspensions of m
 ineral colloidal plates and spheres - Prof. Henk Lekkerkerker\, University
  of Utrecht\, Netherlands
DTSTART:20110218T140000Z
DTEND:20110218T150000Z
UID:TALK29250@talks.cam.ac.uk
CONTACT:Erika Eiser
DESCRIPTION:In the early 1950’s Noble Prize winner Paul J.Flory visited 
 Nagoya University. During this visit two young researchers from the Physic
 s Department of Nagoya University\,Sho Asakura and Fumio Oosawa reported u
 npublished theoretical results on two bodies immersed in a solution of non
 adsorbing polymer chains showing that an attractive interaction appears [1
 ]. The very positive response of Flory resulted in submission of this work
  leading to a seminal paper with the first theoretical prediction of what 
 is now known as the depletion force [2]. Starting in the late 1950s it was
  observed that the addition of non-adsorbing polymers to colloidal suspens
 ions may lead to a phase separation in a colloid-rich and polymer-rich pha
 se Such polymer induced phase separations are very important not only for 
 colloid science but also in industrial and biological systems [3]. It has 
 also been realised that procedures based on the depletion interaction have
  the potential to enable powerful and cost-effective fabrication approache
 s to materials based on self organized colloidal structures. In this talk 
 I will discuss experiments performed in collaboration with Louise Bailey (
 Schlumberger Cambridge Research) and Geoff Maitland (Imperial College Lond
 on) on mixed suspensions of mineral colloidal plates (Hectorite\,Montmoril
 lonite\,Gibbsite) and small silica spheres. The small silica spheres act a
 s depletion agents. On the one hand we observe liquid crystals at low coll
 oid concentrations but also nonequilibrium states such as colloidal glasse
 s and colloidal gels.Attempts to understand this complex equilibrium and n
 on equilibrium phase behaviour will be presented .It appears that the deve
 lopment of the field is hampered more by conceptual locks than by factual 
 locks\n\n1 F.Oosawa .Hyo-Hyo Rakagu.Autobiography \,Nagoya\,2005\n2 S.Asak
 ura and F.Oosawa\,J.Chem.Phys.\,22:1255(1954) \n3For a historical overview
  on depletion effects and manifestations of depletion effects of biologica
 l and technological interest see\nH.N.W. Lekkerkerker and R Tuinier Deplet
 ion Interaction and Phase Behaviour in Colloidal Dispersions Springer  To 
 appear May 2011\n\n
LOCATION:Pippard Lecture Theatre\, Cavendish Laboratory
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