Berlin 2012 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 25: Poster: Stress Relaxation in Polymers - From single molecules to biological cells (joint focus with BP)

CPP 25.6: Poster

Mittwoch, 28. März 2012, 11:00–13:00, Poster A

"Stress relief" via embedding of cyclopropane derivatives in polymers — •Miriam Wollenhaupt and Dominik Marx — Lehrstuhl für Theoretische Chemie, Ruhr-Universität Bochum

Due to their special physical properties such as elasticity, breaking strength, chemical and thermal stability, polymers are widely used. But continuous strain causes weakening of the polymer strands and, therefore, leads to material failure. The embedding of mechanophores (stress-responsive chemical groups that undergo a chemical reaction when exposed to a mechanical force) in the single polymer chains can provide a "stress relief".

Under mechanical forces, gem-dichlorocyclopropanes incorporated along the backbone of cis-polybutadiene exhibit an electrocyclic ring opening accompanied with a chlorine migration[1].

Besides the practical aspects, theoretical investigations on cis- and trans-1,1-dichloro-2,3-dimethylcyclopropane unveil a field of striking features, such as a lack of selectivity at high forces or unexpected branching ratios[2]. We used static calculations to investigate the change of electronic properties along the reaction pathways under different forces. The analysis of wavefunction and electron density was performed using Natural Bond Orbitals and Quantum Theory of Atoms In Molecules.

[1] J. Am. Chem. Soc., 2009, 131, 10818–10819

[2] Angew. Chem. Int. Ed., 2011, 50, 7105–7108