Molecular investigation of the swelling behaviour of polymer model networks

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The project consists of two parts that focus on a better understanding of entanglements and reversible bonds in polymer networks, respectively.In the first part of the project, a suitable model shall be developed for the deformation of ideal networks that consist solely of entanglements. Thiss occurs based upon slip tube models, preceeding results on the swelling of Olympic gels, and additional simulation data on the deformation and swelling of ideal slide-ring gels and Olympic gels, which are contributed by the current project. This model for networks of entanglements shall be extended to model real slide-ring gels with a multitude of cyclodextrine in order to better understand the elasticity of these networks and the interplay of entanglements and the confined diffusion of cyclodextrine along the chains during swelling and deformation. To this end, the mutual influence of junctions and entanglements on the non-affinity of swelling and deformation should be investigated using a series of Olympic gels and/or slide-ring gels with an increasing amount of additional covalent cross-links. It is the goal of these investigations, to develop a quantitative model also for the non-affine contributions to deformation and swelling of conventional polymer networks.The theory about the recombination dynamics of reversible bonds shall be extended in the second part of the project to incorporate stress-induced breakage of bonds and entangled networks. The simulation of the deformation and energy dissipation of partially reversible model-networks has the goal to quantify the collective rearrangements and stress relaxation in consequence of a breaking bond and to develop a model for this process. The impact of the architecture of the molecular building blocks on the relaxation of partially reversible networks shall be analyzed and understood using two classes of model networks (stickers along the chains between junctions and stickers on the ends of star arms or branched polymers).