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SUMMARY:Multivariant gradient assemblies of oligomers and polymers on flat
  surfaces - Prof. Jan Genzer\, North Carolina State University\, USA.
DTSTART:20110304T140000Z
DTEND:20110304T150000Z
UID:TALK29429@talks.cam.ac.uk
CONTACT:Erika Eiser
DESCRIPTION:We will discuss the formation and properties of surface-grafte
 d monolayer and macromolecular assemblies with position-dependent physico-
 chemical characteristics on flat substrates.  In the first part of the pre
 sentation\, I will present results from high resolution X-ray synchrotron 
 measurements in combination with computer simulation studies\, which estab
 lish that vapor deposition of organosilanes under confinement follows “p
 ropagating front” mechanism rather than conventional diffusion.  These w
 avefronts do not follow the constant width predicted by mean-field growth 
 models widely assumed to model such ‘self-propagating’ or ‘autocatal
 ytic’ growth processes.  Instead\, the interface progressively roughens 
 in time and this interfacial broadening is described by a power-law growth
 \, corresponding to the propagating front motion.  Properties of wavefront
 s propagating from a single direction as well as those involving counter-p
 ropagating wavefronts involving different chemical moieties will be discus
 sed.  In the second part\, I will describe methods for generating polymer 
 assemblies comprising gradual variation of grafting density () and mole
 cular weight (MW) of the grafted polymers.  A simple extension of the latt
 er approach will facilitate the generation of surface grafted block copoly
 mers with gradually varying compositions.  I will document that by combini
 ng the individual gradients\, i.e.  and MW\, one can produce complex su
 bstrates in which two material properties change independently in two orth
 ogonal directions.  I will demonstrate that such multivariant polymer brus
 h assemblies represent universal soft material scaffolds that can be utili
 zed in adjusting the spatial distribution of non-polymeric objects\, such 
 as nanoparticles and proteins\, and can be used in controlling the adhesio
 n of living cells on surfaces and studying the phase behavior of multicomp
 onent surface-tethered polymer assemblies.
LOCATION:Pippard Lecture Theatre\, Cavendish Laboratory
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