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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!
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