Correlation of molecular dynamic and mechanical properties in the linear and non-linear regime of comb-like homopolymers via FT-rheology and multi-quantum-NMR-spectroscopy
Experimental and Theoretical Physics of Polymers
Final Report Abstract
A set of model samples, i.e., a partially deuterated comb and a fully protonated comb has been synthesized and characterized using SEC, rheology, FT-rheology, and TD-NMR as proposed in the project. The model system was characterized using rheology, FT-rheology, dielectric spectroscopy and TD-NMR. To do so, deuterated isoprene monomer has been synthesized on a smaller than expected scale, due to substantial experimental difficulties. To increase the understanding of the rheological nonlinear behavior, the model for linear monodisperse homopolymers has been expanded to describe bidisperse blends, which have two distinct relaxation times. The intrinsic nonlinearitiy of the third showed an unexpected cubic dependence on the concentration. The observed relaxation times of linear rheology and FT-rheology agreed with each other and are consistent with broadband dielectric spectroscopy. The resulting knowledge has been transferred to polymer combs. In summary, polymer combs show the expected two relaxation processes, which can be assigned to the relaxation of the backbone and the sidechains. Moreover, the relaxation times obtained from FT-rheology in the bidisperse blends can be predicted with analytical models applied to the linear viscoelasticity experiments. Exciding the proposal also broadband dielectric spectroscopy has been employed to characterize PI linear bidisperse melts and PI combs. Special emphasis was given to a derivative method to allow for further 1.5 decades additional experimental range in the low frequency regime. The relaxation times obtained from linear rheology, FT-rheology and BDS are found to be the same within experimental limitations. Due to limited sample availability, the NMR part of the project could mainly provide support for the final stages of two other DFG projects, within which significant progress with regards to understanding the physics stretched elastomers and the NMR detection of polymer chain relaxation modes could be achieved. First NMR results on finally available comb samples support that one of the primary goals of the project, i.e. selectively detecting the relaxation of the arms and the backbone of comb polymers, can be reached. However, limited sample availability and an unexpected degradation process have slowed down the progress towards reaching the intended goals of the project. Work along these lines, funded by other sources, is still ongoing.
Publications
- (2016) Effect of Molecular Weight, Polydispersity, and Monomer of Linear Homopolymer Melts on the Intrinsic Mechanical Nonlinearity 3Q0 (ω) in MAOS. Macromolecules 49:3566–3579
Cziep MA, Abbasi M, Heck M, Arens L, Wilhelm M
(See online at https://doi.org/10.1021/acs.macromol.5b02706) - (2017) Orientation-dependent proton double-quantum NMR build-up function for soft materials with anisotropic mobility. Solid State Nucl Magn Reson 82-83:22–28.
Naumova A, Tschierske C, Saalwächter K
(See online at https://doi.org/10.1016/j.ssnmr.2017.01.006) - (2018) Characterization of Partially Deuteron Labeled Polymer Model Systems with (FT-)Rheology and TD-NMR Techniques, Biennial Meeting of the GDCh-Division of Macromolecular Chemistry together with SFB 1176 "Molecular Structuring of Soft Matter", Karlsruhe, Germany
Jonas S. Keller
- (2018) Time-Domain NMR Observation of Entangled Polymer Dynamics: Focus on All Tube-Model Regimes, Chain Center, and Matrix Effects. Macromolecules 51:4108–4117
Trutschel M-L, Mordvinkin A, Furtado F, Willner L, Saalwächter K
(See online at https://doi.org/10.1021/acs.macromol.8b00443) - (2019) (FT-)Rheology Polymer Model Systems and TD NMR on Partially Deuterated Polymers, DRG-Symposium, BAMF, Berlin
Jonas S. Keller
- (2019) Microscopic State of Polymer Network Chains upon Swelling and Deformation. Macromolecules 2019 52 (13), 5042-5053
Naumova A, Agudelo DC, Villar MA, Vega DA, Valentin JL, Saalwächter K
(See online at https://doi.org/10.1021/acs.macromol.9b00971) - (2019) Time Domain NMR and (FT-)Rheology Characterization of Polymer Model Systems, European Polymer Congress, Crete, Greece
Jonas S. Keller
