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The Relationship between Grafting Density and the Solution Structure of Polynorbornene Bottlebrush Polymers

Published

Author(s)

Daniel Sunday, Adam Burns, Tyler Martin, Alice Chang, Robert Grubbs

Abstract

Developing an understanding of the relationships between structure and conformation in complex macromolecular architectures is key for designing materials with targeted properties in applications ranging from sensors to tissue replacement. Bottlebrush polymers are an important class of materials which consist of sidechains grafted along a linear backbone. There has been a significant effort to understand structure-property relationships of bottlebrush polymers in solution, with experiments and simulations mapping the impact of parameters such as sidechain length, backbone length and concentration. Improvements in the ability to control the graft density has resulted in greater interest in understanding how the sidechain density influences polymer conformation. However, the impact of graft density on bottlebrush polymers with a polynorbornene backbone remains relatively unexplored. Here we examine two sets of polynorbonene based bottlebrush polymers with polystyrene sidechains where the graft density varies between 40 % and 100%. The solution conformation of these materials in a good solvent, toluene, is probed through small angle neutron scattering measurements. Fitting this data with a shape-based model allows for the extraction of parameters such as the radius of gyration and persistence length. Measurements at multiple concentrations enables a Zimm plot analysis for determination of second virial coefficients, which are compared to both linear polymers and other bottlebrush systems. Finally, the scaling of the radius of gyration with respect to molecular weight is examined and determined to be 0.48, similar to the mass scaling of randomly branched polymers in a good solvent.
Citation
Macromolecules

Citation

Sunday, D. , Burns, A. , Martin, T. , Chang, A. and Grubbs, R. (2023), The Relationship between Grafting Density and the Solution Structure of Polynorbornene Bottlebrush Polymers, Macromolecules, [online], https://doi.org/10.1021/acs.macromol.3c01436, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=935102 (Accessed February 23, 2024)
Created September 14, 2023, Updated February 8, 2024