Side Chain Dynamics of Poly(norbornene)‐g‐Poly(propylene oxide) Bottlebrush Polymers. Issue 7 (15th January 2023)

• Record Type: Journal Article
• Authors: Bichler, Karin J.; Jakobi, Bruno; Klapproth, Alice; Tominaga, Taiki; Mole, Richard A.; Schneider, Gerald J.
• Is Part Of: Macromolecular rapid communications. Volume 44:Issue 7(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2023-01-15
• Subjects: bottlebrush polymers -- neutron scattering -- segmental dynamics; Macromolecules -- Periodicals; Polymers -- Periodicals; Chemistry -- Periodicals; 547.705
• DOI: 10.1002/marc.202200902
• Languages: English
• ISSNs: 1022-1336

Abstract

Abstract: The segmental dynamics of the side chains of poly(norbornene)‐ g ‐poly(propylene oxide) (PNB‐ g ‐PPO) bottlebrush polymer in comparison to PPO is studied by quasi‐elastic neutron scattering. Having experimental time and length scale information simultaneously allows to extract spatial information in addition to relaxation time. Tethering one end of the PPO side chain onto a stiff PNB backbone slows down the segmental relaxation, over the length and time scales investigated. The power law dependence of the relaxation time on the momentum transfer, Q, indicates a more heterogeneous relaxation pattern for the bottlebrush polymer, whereas the linear PPO has less deviations from a homogenous relaxation. Similar conclusions can be drawn from the time dependent mean square displacement, 〈 r 2 ( t )〉, and the non‐Gaussian parameter, α 2 ( t ). Herein, the bottlebrush polymer shows a more restricted dynamics, whereas the linear PPO reaches 〈 r 2 ( t )〉∝ t 0.5 at the highest temperature. The deviations from Gaussian behavior are evident at the α 2 ( t ). Both samples show a decaying α 2 ( t ). The non‐Gaussian parameter supports the results from the power law dependence of the relaxation times, with lower α 2 ( t ) values for PPO compared to those for PNB‐g‐PPO, pointing to less deviations from Gaussian behavior. Abstract : The segmental relaxation of poly(norbornene)‐g‐poly(propylene oxide) bottlebrush polymers is studied in comparison to linear poly(propylene oxide) by using the incoherent intermediate scattering function, obtained by quasi‐elastic neutron scattering (QENS). Hereby, the relaxation slows down together with a broadening of the distribution of relaxation time once the side chain is attached to the backbone independent of the length scale.