Fast Dynamics in Polymers

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In this program the dynamic of polymeric systems is studied experimentally in a broad temperature range, from deep in a solid state up to deep in a liquid state. The main subject of the program is analysis of the fast dynamics in different polymers. This dynamics includes cooperative molecular motion on a nanometer scale. This motion is a necessary precursor of many slower processes and strongly influences macroscopic properties of the material. The main methods are light and neutron scattering spectroscopy. The combination of these two techniques gives detailed information on the fast dynamics spectra and on peculiarities of the motion on a molecular level. Different theoretical approaches, from Mode-Coupling Theory to model of Asymmetric Double-Well Potentials, are tested and used for analysis of the experimental data. New model approximations that would consistently describe the data in a broad temperature and frequency ranges are discussed and developed. The program is a starting point for broad collaboration between different groups (experimental, theory and computer simulations) working in the field of polymer dynamics. The results of the program will bring better understanding of microscopic picture of the fast dynamics and its peculiarities in polymeric systems and will lead to development of consistent theoretical description of the dynamics in solid and liquid states%%%Molecular motion is a key for many macroscopic materials properties. The proposed here research is concentrated on analysis of cooperative molecular motion on a molecular frequency (GHz-THz range) and length (nanometer) scales. The results of the research will strongly influence the development of the field of polymer dynamics and dynamics of disordered materials and bio-polymers in general. The knowledge received I the result of the program can be useful for designing of new plastics with desired properties, especially for high-frequency applications (optical comunications, computers, optical memory storage devices).