by
Prof.Claudio Zannoni(Dipartimento di Chimica Industriale "Toso Montanari", Università di Bologna)
→
Europe/Rome
Aula Careri (Dipartimento di Fisica - Ed. G. Marconi)
Aula Careri
Dipartimento di Fisica - Ed. G. Marconi
Description
For a variety of practical applications, ranging from displays to organic
electronics devices such as organic field effect transistors, solar cells
etc., liquid crystals are employed in very thin films, where surfaces play an
essential role. In particular, the type of director orientation, i.e. planar
(either uniform or degenerate) or tilted or perpendicular with respect to the
interface, as well as the extent of anchoring and orientational order, is key
to the proper functioning of the various devices. Behaviour of liquid
crystals at interfaces with vacuum, crystalline or amorphous solids, polymers
or other functionalized surfaces is also of fundamental interest to
understand how molecules forming liquid crystals interact with their
environment. Thus, it is somewhat surprising that surface effects are still
in most cases described only empirically, while little is known on their
molecular origin. In this talk we shall show that computer simulations for
coarse-grained models (e.g. for the attractive–repulsive Gay-Berne model
[1]) and for systems at full atomistic resolution [2-8] start to shed some
light on the interfacial behavior of liquid crystals. In particular, we shall
briefly summarize the main features of the models and we shall show examples
for the prediction of the alignment and anchoring of nematics (cyanobiphenyls
in particular) in freely suspended films [4] or at the interface with
different solid surfaces e.g. silicon [5], crystalline and glassy silica with
different roughness [6], polymers [7] as well as soft self-assembled
monolayers [8].
Note:
Il Prof. Claudio Zannoni (email: claudio.zannoni@unibo.it) è professore
ordinario di Chimica Fisica presso il Dipartimento di Chimica Industriale
"Toso Montanari" dell'Università di Bologna e si occupa prevalentemente di
cristalli liquidi e materiali soffici anisotropi utilizzando approcci
teorici, simulazioni al calcolatore e tecniche spettroscopiche, è autore di
oltre 250 pubblicazioni su riviste internazionali con un h-index pari a 41
(scopus) ed ha tenuto oltre 300 talk o seminari su invito.
Tra i numerosi incarichi attuali e passati è da menzionare che dal 1998 è
presidente della International School of Liquid Crystals, presso il Centro
Ettore Majorana ad Erice e che tra il 2012 ed il 2016 è stato presidente
della International Liquid Crystal Society (ILCS). Un Curriculum Vitae esteso
del Prof. Claudio Zannoni si può trovare al seguente link:
http://claudiozannoni.fci.unibo.it/
References:
[1] D. Vanzo, M. Ricci, R. Berardi and C. Zannoni, Wetting behaviour of
nematic nanodroplets on planar surfaces, Soft Matter, 12, 1610, 2016.
[2] M.F. Palermo, A.Pizzirusso, L.Muccioli, C. Zannoni, An atomistic
description of the nematic and smectic phases of 4-n-octyl-4'cyanobiphenyl
(8CB), J.Chem.Phys. 138, 204901, 2013.
[3] Y. Olivier, L. Muccioli, C. Zannoni, Quinquephenyl: the simplest rigid
rod-like nematic liquid crystal. Or is it? An atomistic simulation,
ChemPhysChem 15, 1345, 2014.
[4] M.F. Palermo, L. Muccioli, C. Zannoni, Molecular organization in freely
suspended nano-thick 8CB smectic films. An atomistic simulation,
PhysChemChemPhys, 17, 26149, 2015.
[5] A. Pizzirusso, R. Berardi, L. Muccioli, M. Ricci and C. Zannoni,
Predicting surface anchoring. Molecular organization across a thin film of
5CB liquid crystal on silicon, Chemical Science 3, 573. 2012.
[6] O.M. Roscioni, L. Muccioli, R. Della Valle, A. Pizzirusso, M. Ricci and
C. Zannoni, Predicting the anchoring of liquid crystals at a solid surface:
5-cyanobiphenyl on cristobalite and glassy silica surfaces of increasing
roughness, Langmuir 29, 8950, 2013.
[7] M.F. Palermo, F. Bazzanini, L. Muccioli, C. Zannoni, Polymer-liquid
crystal interface: a molecular dynamics study, submitted (2017)
[8] O.M. Roscioni, L. Muccioli, C. Zannoni, Liquid crystals anchoring on soft
surfaces: from planar to homeotropic ordering for 5CB on SAM, ACS Applied
Materials & Interfaces 9, 11993, 2017.
