Soft Matter Geometry _amp; Materials by yurtgc548

VIEWS: 2 PAGES: 27

									   Soft Matter:
Geometry & Materials
                Mark Bowick
             Syracuse University




       Saturday Morning Physics 10/23/2004
Polymers
Polymer3D.pdb
   Free Energy
   F = U - TS

Energy          Entropy
     Nature’s Task: Minimize F
• U favors soft (low
  energy) fluctuations




• S favors frequently
  occurring
  configurations
“Polymer Sheets”=Membranes




   Gertrude Goldschmidt (Gego): Esfera 1976: stainless steel wire
   – 97 X 88 cm (de Cisneros Collection, Caracas, Venezuela)
365,000X
           J.F. Hainfeld and T.L. Steck, J. Supramol. Struct. 6, 301 (1977)

           (courtesy Leo Van Hemmen)                10,000X
   Packing in 2 dimensions
           Flatland

Colloids              Bees
Zentsuji watermelons
Sphereland
Triangular lattices
A triangular lattice cannot be wrapped
        perfectly on the sphere

                       V–E+F=2


                      (6  c ) 12
                      i
                                     i

                     Coordination No. of vertex i
  Cover of Physical Review Letters
Bowick, Cacciuto, Nelson & Travesset
         28 October 2002
Colloidosomes
Prediction: Bowick, Nelson & Travesset: 1999
            Bausch, Bowick et. al. Science 299, 1716 (2003)
                                        Central Defect screened
Isolated Defect
                                        by Dislocations!!!
Simulations
 Controlling the valence:




4 defects at the vertices of a
tetrahedron result when
nematogens coat a sphere




D.R. Nelson, Nano Letters (2002)
Donut Defects
                         Conclusions
•   Soft is Complex
•   Soft is Rich
•   Soft is Hard
•   Soft is Beautiful



    Thanks to the Department of Energy, National Science Foundation,
                   Syracuse University and all of you!

								
To top