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Published August 25, 2020 | Accepted Version + Supplemental Material
Journal Article Open

Concentration Dependence of the Size and Symmetry of a Bottlebrush Polymer in a Good Solvent


Bottlebrush polymers consist of a linear backbone with densely grafted side chains which impact the rigidity of the molecule. The persistence length of the bottlebrush backbone in solution is influenced by both the intrinsic structure of the polymer and the local environment, such as the solvent quality and concentration. Increasing the concentration reduces the overall size of the molecule because of the reduction in backbone stiffness. In this study, we map out the size of a bottlebrush polymer as a function of concentration for a single backbone length. Small-angle neutron scattering measurements are conducted on a polynorbornene-based bottlebrush with polystyrene side chains in a good solvent. The data are fit using a model which provides both the long and short axis radius of gyration (R_(g,2) and R_(g,1), respectively), providing a measure for how the conformation changes as a function of concentration. At low concentrations, a highly anisotropic structure is observed (R_(g,2)/R_(g,1) ≈ 4), becoming more isotropic at higher concentrations (R_(g,2)/R_(g,1) ≈ 1.5). The concentration scaling for both R_(g,2) and the overall Rg is evaluated and compared with predictions in the literature. Coarse-grained molecular dynamics simulations were also conducted to probe the impact of concentration on bottlebrush conformation, showing qualitative agreement with the experimental results.

Additional Information

© 2020 American Chemical Society. Received: May 19, 2020; Revised: July 11, 2020; Published: August 7, 2020. This work benefited from the use of the SasView application, originally developed under NSF award DMR-0520547. SasView contains code developed with funding from the European Union's Horizon 2020 research and innovation programme under the SINE2020 project, grant agreement no 654000. A.B.B. acknowledges support from the National Research Council Research Associateship Program. The authors acknowledge the nSoft consortium for providing access to the NGB 10m SANS instrument. The authors declare no competing financial interest.

Attached Files

Accepted Version - nihms-1686062.pdf

Supplemental Material - ma0c01181_si_001.pdf


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August 19, 2023
October 20, 2023