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Seminário de Matéria Condensada

O seminário de Materia Condensada desta semana será apresentado por
Olivier Pierre-Louis, do Institut Lumière Matière, Universitè Lyon 1. O título do seminário é
"Adhesion of membranes on patterned substrates: the case of graphene".
Um resumo pode ser encontrado abaixo.

Data: 07/08, quinta-feira
Horário: 11h
Local: sala 201.


Substrate patterning is shown to be a convenient method to control the
adhesion of membranes and filaments for  carbon nanostructures (e.g.
graphene and nanotubes),
and for objects of biological interest (such as lipid membranes and
actin filaments).
From a simple one-dimensional model, we find that membranes and filaments on
patterned substrates exhibit a series of partial unbinding
transitions, and a complete unbinding transition when thermal
fluctuations are negligible (at low temperatures) [1,2].

We discuss more precisely the adhesion of graphene,
in collaboration with two experimental groups in Lyon, France [3],
and in Maryland, USA [4]. For graphene on bare SiO2[3], we find an
unbinding transition between 2 and 3 layers when increasing the number
of layers with few-layers graphene.
These results are in agreement with our one-dimensional model.
However, when SiO2 nanoparticles are intercalated between graphene and
the substrate[4],
we find not only unbinding, but also a wrinkling transition.
Quantitative agreement is achieved at low nanoparticle density with
simple models
showing the competition between stretching and bending elasticity.
However, the unbinding transition involves collective effects
involving several nanoparticles[5].

[1] Adhesion of membranes and filaments on rippled surfaces,
O. Pierre-Louis, Phys. Rev. E 78, 021603 (2008).
[2] Pattern-induced thermal unbinding of filaments
O. Pierre-Louis,  Phys Rev E 83 01181 (2011).
[3] Pressure-mediated Doping in Graphene
J. Nicolle, D. Machon, P. Poncharal, O. Pierre-Louis, Alfonso San-Miguel
Nano Lett 13 043017 (2011).
[4] The princess and the pea at the nanoscale: Wrinkling and unbinding
of graphene on nanoparticles
M. Yamamoto, O. Pierre-Louis, J Huang, M. Fuhrer, T.L. Einstein, W.G. Cullen.
Phys Rev X (2012).
[5] O. Pierre-Louis, unpublished (2014).