Abstract
The segmental dynamics of bottlebrush polymers with a stiff backbone and flexible side chains has been studied. The segmental relaxation time of side chains attached to a flexible backbone follows the same trend as linear polymers, an increase with the increasing molecular weight, but is slowed down compared to their linear counterparts. Theoretical work predicts a reversal of the molecular weight dependence of the relaxation time for stiff backbones. As a model for a stiff-g-flexible system, bottlebrushes with poly(norbornene) backbone and poly(propylene oxide) side chains, PNB-g-PPO, at a uniform grafting density have been synthesized and characterized with quasi-elastic neutron scattering. Indeed, the anticipated reversed dynamics was found. Increasing the side chain length decreases the segmental relaxation time. This indicates the importance of the characteristics of the grafting site beyond a simplified picture of an attached side chain. The mean square displacement shows a similar trend with longer side chains exhibiting a larger displacement.
| Original language | English |
|---|---|
| Article number | 084901 |
| Journal | Journal of Chemical Physics |
| Volume | 160 |
| Issue number | 8 |
| DOIs | |
| State | Published - Feb 28 2024 |
| Externally published | Yes |
Funding
The authors acknowledge funding from the U.S. Department of Energy under Grant No. DE-SC0019050. Furthermore, this work is based on experiments performed at the Swiss spallation neutron source SINQ, Paul Scherrer Institute, Villigen, Switzerland, under Proposal No. 20222348. Mass spectrometry experiments were performed at the LSU Mass Spectrometry Facility (MSF). The Bruker UltrafleXtreme MALDI instrument was supported by NIH (Grant No. 1S10RR024520-01A1). The authors acknowledge funding from the U.S. Department of Energy under Grant No. DE-SC0019050. Furthermore, this work is based on experiments performed at the Swiss spallation neutron source SINQ, Paul Scherrer Institute, Villigen, Switzerland, under Proposal No. 20222348. Mass spectrometry experiments were performed at the LSU Mass Spectrometry Facility (MSF). The Bruker UltrafleXtreme MALDI instrument was supported by NIH (Grant No. 1S10RR024520-01A1).