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Claudio Zannoni

Alma Mater Honorary Professor

Alma Mater Studiorum - Università di Bologna


Keywords: liquid crystals ESR spin probe spectroscopy computer simulations atomistic simulations nanotechnology molecular dynamics colloids fluorescence depolarization molecular modelling Monte Carlo organic electronics display NMR

The Main Research themes and Expertise are:
Molecular Modelling, Computer Simulations (Monte Carlo and Atomistic and Coarse Grained Molecular Dynamics) and Spectroscopic (Fluorescence, ESR, NMR) investigations of
Liquid Crystals, Polymers,  Membranes, Proteins and other  Soft Materials in the bulk or nanoconfined.
We aim to clarify the mechanisms of formation of specific molecular organizations and nanostructures starting from molecular properties.
We are interested both in static (order parameters, distributions) and dynamics (correlation functions) in a variety of systems and in particular in anisotropic systems in the bulk, nanoconfined, and close to surfaces
We develop methodologies for simulations (e.g. to investigate chirality in proteins) and for analyzing experimental data. For instance we  analyze ESR spin probe technique  data to obtain order and fluidity  in nanoconfined nematics (polymeric holographic masks), or in nematics with dispersed nanoparticles or in polymer dispersed liquid crystals  (PDLC, H-PDLC)).

Most of the research activity of C. Zannoni  and his group  is in the field of liquid crystals and anisotropic soft materials using theory, computer simulations and various spectroscopical techniques. The work has led to around 250 publications (H=40) in international journals or multi-author books, particularly on: Modeling and Computer Simulations (Monte Carlo, Molecular Dynamics) of lattice (Lebwohl-Lasher), molecular (Gay-Berne) and Atomistic Models and Statistical Theories of bulk and confined Liquid Crystals.

Lattice models are used to investigate orientational properties and phase transitions of a variety of 3D, 2D, 1D bulk systems, but also to model displays  and to simulate defects in droplets and in hybrid films and the effect of external fields. We study nanoconfined systems, in particular the effects on order and memory of nanoparticles and polymer fibrils dispersed in nematics. We also investigate differences in the optical textures of uniaxial and biaxial  nematics.

Gay-Berne (GB) systems are molecular resolution models employed to study various bulk phases and their transitions. Modeling of liquid crystal properties resulting by simple changes in the molecular structure, particularly due to changes in shape (rod, disk, tapered, bowlic) or electrostatic effects . We have simulated at molecular level liquid crystal displays and developed generalized versions of the GB potential that allow non-uniaxial, chiral, soft  and deformable shapes. Using these models we have succeeded in simulating thermotropic biaxial nematics and a ferroelectric nematic designed from tapered molecules by suitably combining repulsive and attractive interactions. We have extended the GB model further to model LC polymers and elastomers as anisotropic beads and springs in bulk and nanoconfined systems.We are now interested in studying (1) LC with the inclusion of nanoparticles, fullerene and nanotubes (2) surface wetting properties

Atomistic simulations of Liquid Crystals. We model geometry and charge distribution of liquid crystal (LC) molecules using Quantum Chemistry techniques to simulate and predict, using Molecular Dynamics, their properties and phase transitions. Recently we have succeeded in obtaining LC phase transition temperatures and in reproducing and predicting for the first time detailed bulk and  properties for liquid crystals (e.g. cyanobiphenyls) and their alignment close to solid surfaces (silicon, glass, ..). 
We have also investigated a variety of organic functional materials for applications in organic electronics, studying the relation of charge and energy transport to molecular organizations using atomistic simulations.
We are now interested in extending the atomistic predictive work to other  solid and liquid interfaces. As for organic electronic applications we are also particularly interested in ordering at surfaces and ensuing properties.

Development of theories and of data analysis methodologies for the study and characterization of liquid crystalline materials, including polymers and lipid membranes, with various techniques: Fluorescence Depolarization, ESR, NMR, Dielectric Relaxation, particularly for the determination of their order parameters and dynamics.
ESR spin probe methods are now used to study probes in nematic with dispersed nanoparticles and examine changes in order and dynamics.

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