NEW ROUTES TO THE STRUCTURE OF DISORDERED POLYMERS THROUGH COUPLED SCATTERING AND MODELLING. GR Mitchell, Polymer Science Centre, JJ Thomson, Physical Laboratory, University of Reading Whiteknights Reading RG6 6AF UK

The local structure of disordered polymers remains a challenging area of polymer science. The interactions between chain segments lie at the heart of many central issues including miscibility in blends, crystallisation of non-periodic chains and in deformation processes. Although simulation procedures such as molecular dynamics are powerful tools, their complete reliance on the correctness of the force-fields employed limits their usefulness in many cases. We have developed atomistic molecular modelling tools which allow the tremendous level of information in a neutron or x-ray scattering pattern to be exploited directly in the model construction. The particular utility of broad Q neutron scattering with an extended Q range and the possibility of isotopic substitution will be highlighted. These tools are essentially Monte Carlo procedures in which the fit between calculated and experimental structure factors play the same role as the energy of the system in a conventional simulation. A particular feature of these procedures is the manner in which the chemical connectivity is directly involved. Examples demonstrating the power of these new procedures will be given. We have been able to extract the level of orientational segmental correlations has been obtained from experimental data alone for a series of polymers with differing degrees of backbone flexibility. The possibility of linking these procedures with energy based methods will be discussed.