Workshop on:

Computational Methods
for Polymers and
Liquid Crystalline Polymers

16-22 July 2003 - Erice ITALY

"E. Majorana" Centre for Scientific Culture ERICE (TP)

Workshop Objective

Liquid crystals, polymers and polymer liquid crystals are soft condensed matter systems of major technological and scientific interest. In liquid crystals the orientational order of the constituent molecules is associated with a reduced or absent translational order. This combination of properties confers on liquid crystalline systems a combination of fluidity (liquid-like properties) and anisotropic properties, similar to those of a crystal. Orientational order can be controlled easily by the application of external fields, leading to the spatial switching of bulk properties in response to external stimuli. This provides the basis for a wide range of technological applications, including displays, optical switches, adaptive optics for telescopes and many other electro-optical devices.
Polymers are ubiquitous. In nature, polymers in the form of proteins and nucleic acids form the basis of life itself. In modern society, man-made polymers are essential in clothing, packaging, structural materials and in a range of other areas to numerous to list. Knowledge of polymer structure and dynamics is essential in understanding biological processes and in designing new materials across a wide-range of applications. The latter is particularly important in view of the growing scientific interest in novel polymeric materials with complicated architectures: graft and star copolymers, hyperbranched and dendritic materials, amphiphilic polymers and polyelectrolytes.

An understanding of the macroscopic properties of such complex systems and of their many strange and interesting behaviour patterns at the molecular level can nowadays only be attained using computer simulations, possibly with the complement of approximate statistical mechanical theories.
Simulations of low molar mass liquid crystals are based on the same general Monte Carlo and Molecular Dynamics techniques used for simple fluids, but present a number of problems and peculiarities connected with the intrinsic properties of mesophases such as their long-range order and their anisotropy. This requires in turn the development of suitable algorithms for the calculation of static properties such as order parameters, correlation functions, elastic constants and in general tensorial observables as well as dynamic quantities such as diffusion tensors, viscosities, susceptivities etc. Other aspects specific to liquid crystals, as opposed to simple fluids, concern the simulation of topological defects and the direct, microscopic level, simulation of simple devices and displays. Various classes of models exist at different special resolutions, ranging from atomistic to molecular and coarse-grained lattice models. A major challenge exists in linking these models together to provide a coherent coarse-graining strategy to bridge the microscopic and mesoscopic regimes.
Polymer theory has a longer history than that of liquid crystals with statistical mechanics methods and more recently simulations, which have dealt successfully with many of the structural, elastic and mechanical properties of polymers and elastomers. The computer simulation of polymers has developed independently with the need to develop methods to account for specific problems (e.g. chain flexibility and entanglement, glassy behaviour, swelling, long time-scales) that inevitably arise when macromolecules have to be dealt with. Several simulation methods are available currently. These range from lattice models, bead-and-spring polymers and (in some cases) atomistic resolution models. The problems attacked range from those posed by modelling of polymerization and cross-linking processes, to studies of the bulk properties of melts, solutions and composites.
In general each of the two fields has developed its own set of tools and specialized procedures. It is however increasingly clear that a forum for discussing the relation and potential cross-fertilization between these connected areas would be very desirable. This is particularly apparent for a number of experimental systems like, e.g. polymer liquid crystals and anisotropic gels where the different fields necessarily merge.

The objective of the Workshop is to provide a state of the art review of the rapidly evolving field of computer simulation studies of polymers and liquid crystals. An effort will be made to assess the possibilities of a coherent description of these themes that have independently developed, and of comparing and extending the theoretical and computational techniques developed in the different areas with a view to cross-fertilization. This is particularly important in view of improving the knowledge and the development of the simulations of liquid crystalline polymers and liquid crystal elastomers.

The Workshop aims to bring together a number of top specialists in the field that will lecture on topics that, in many cases, they themselves have pioneered. Participants will be provided with a clear view of the field and of the different approaches available. The format of the lectures will be reviews, while some specific topics will be covered by contributed papers in one afternoon. All participants will also have the opportunity to present their recent work in a discussion forum and poster sessions in the evening. Ample space will be devoted to discussing the open problems in theory and experiments that computer simulations can now tackle, and informal meetings should lead to new contacts and collaborations. The present state and perspectives of the field will be reviewed in a panel discussion at the end of the meeting.