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SUMMARY:Optimizing the Ordered Self-Assembly of Soft and Hard Nanoscale Bu
 ilding Blocks: Pure Components and Alloys - Professor Fernando Escobedo\, 
 Cornell University
DTSTART:20180830T131500Z
DTEND:20180830T141500Z
UID:TALK109336@talks.cam.ac.uk
CONTACT:Lisa Masters
DESCRIPTION:As meso-scale building blocks\, oligomers\, polymers\, and nan
 oparticles can be tailored in ways that atomic or small-molecule building 
 blocks cannot. Recent progress in synthesis and fabrication methods allow 
 the creation of multi-block oligomers and nanoparticles that vary not only
  in size and chemical composition but also in shape\, rigidity\, branching
  topology\, and spatial functionalization. A key challenge that such bound
 less possibilities present to modelers is the ability to predict the assem
 bling patterns of novel building blocks\, and thus potentially identify ph
 ases with desirable structures and physical\, optical\, electronic\, catal
 ytic or mechanical properties for emerging applications. \nI will describe
  our efforts to optimize the formation of different types of colloidal all
 oys\, which can be seen as the analog of strategies that have already deve
 loped to make useful salts or doped solids from inorganic elements or allo
 ys and intermetallic compounds from metals\, the goal is to advance genera
 l principles and approaches to design the inter-species interactions betwe
 en nanoparticles that optimize the formation of either substitutionally di
 sordered alloys or substitutionally ordered alloys. The work focuses on bi
 nary mixtures consisting of nanoparticle components whose interactions can
  be characterized by asymmetries in entropic and energetic characteristics
 . We have formulated variational principles for enhancing co-assembly beha
 vior with the target type of substitutional order and tested those princip
 les by application to mixtures containing components of diverse size and s
 hape (including polyhedral) and selective interactions that mimic the hybr
 idization of complementary short DNA strands grafted to the nanoparticle s
 urfaces. Some of our specific predictions are consistent with results of n
 anoparticle alloys already realized.\nI will also briefly describe our wor
 k on the phase behavior of polyphilic oligomers\, i.e.\, molecules consist
 ing of several block types\, focusing on cases where a rigid core is one o
 f the constituent blocks. We focus on architectures that can create comple
 x ordered mesophases\, filling some of the gaps in the rich phase behavior
  that has already been mapped experimentally. \nFinally\, I will touch on 
 some of the methods used to simulate these systems and how questions relat
 ed to the optimization of kinetic behavior (beyond thermodynamic stability
 ) could be addressed.\n
LOCATION:Department of Chemistry\, Cambridge\, Unilever lecture theatre
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