Role of Topology on Polymer Dynamics in Rings and their Blends

• Applicants: Dr. Margarita Kruteva; Professor Dr. Siegfried Stapf
• Subject Area: Preparatory and Physical Chemistry of Polymers ; Experimental and Theoretical Physics of Polymers
• Term: since 2026
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 571095035

In this project, we intend to combine neutron scattering and spin-relaxation NMR and diffusion NMR to study the dynamics of ring polymers in different topological environments in order to provide experimental evidence for phenomena predicted by theory and computer simulation. This will involve combinations of molecular weights of ring-ring and ring-linear blends, where, employing partial deuteration, intra- and intermolecular contributions to the dynamics will be studied based on (i) NMR methods focused on spin-lattice, spin-spin relaxation and spin-echo phenomena and covering a large time interval from 10-9 to 10-1 s (ii) quasielastic neutron scattering (QENS), in particular neutron spin echo spectroscopy (NSE), on the timescale 10-9 – 10-6 s, providing spatial resolution from one to tens of nanometers. The experiments will be supported by theoretical investigations focused on the phenomena and functions observed experimentally. Synthesis of the hydrogenated and deuterated poly(ethylene oxide) (PEO) ring polymers will be performed at the JCNS, Forschungszentrum Jülich (FZJ). Polymers (ring and linear) with narrow molecular weight distribution will be characterized by GPC, DLS, NMR etc techniques. Depending on the molecular weight, the characterization method will be chosen. The experiments (neutron scattering and NMR) will be performed on the identical samples. The experimental part of the project assumes the investigation of the dynamics of ring molecules and ring-linear blends on a comprehensive time scale, shedding light on different aspects of ring dynamics. Among them, the origin of sub-diffusive behaviour of the centre-of-mass of the ring in different surroundings: ring-ring and ring-linear blends at different ring concentration. The dynamical parameters will be presented in the form of a phase diagram reflecting the phenomena depending on the molecular weight, blend content and topology. The results are important in biology and material science, where the topology plays an important role. The proof of concept has already been performed by the applicants and requires further systematic investigations. The combination synthesis of narrow distributed ring and linear polymers, neutron scattering (JCNS) and NMR (TU Ilmenau) techniques, and theoretical approach provides the successful implementation of the project. In particular, the gram-scale synthesis of large rings, that assumes highly entangled melt if chains are linear, with narrow molecular weight distribution makes the project unique in the field of polymer physics and chemistry.

• DFG Programme: Research Grants