Towards Probing Structural Transition of Single-Polymer Chains with External Force

Sebastian Belau, Ralf Seidel

Peter Debye Institute for Soft Matter Physics, Leipzig University, Linn├ęstr. 5, 04013 Leipzig

The crystallization of polymers is typically investigated by cooling of a melt and characterizing the process or the finally formed structure with different methods (e.g. DSC, SAXS, NMR spectroscopy). Here we want to follow a different approach and investigate the crystallization at ambient conditions by using mechanical stress. Herby single polymer chains shall be stretched and the structure formation process will be induced by lowering the applied force. This way crystallization as well as structure disruption could be studied. To this end we focus on short polyethylene glycol (PEG) chains of approximately 5 kDa. The application of force to the PEG will be carried out in an optical tweezers setup as well as in a magnetic tweezer setup. For the convenient manipulation as well as for a precise length determination, we started to synthesize PEG-DNA hybrids consisting of a single polymer chain with dsDNA attached to both ends. Herby the reaction of thiol with maleimide and click chemistry with an azide-alkyne reaction is exploited. The successful coupling of one DNA oligomer to the polymer could be shown. Future experiments for binding DNA to two coupling sites of the polymer are planned.