Small‐angle neutron scattering analysis of bottlebrush backbone and side chain flexibility |
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| Authors: | Stacy L Pesek Qiqi Xiang Boualem Hammouda Rafael Verduzco |
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| Institution: | 1. Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas;2. Nanosystems Engineering Research Center for Nanotechnology‐Enabled Water Treatment, Rice University, Houston, Texas;3. National Institutes for of Standards and Technology, Center for Neutron Research, Gaithersburg, Maryland;4. Department of Materials Science and NanoEngineering, Rice University, Houston, Texas |
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| Abstract: | Bottlebrush polymers have densely tethered side chains grafted to a linear polymer backbone, resulting in stretching of both the side chains and backbone. Prior studies have reported that the side chains are only weakly stretched while the backbone is highly elongated. Here, scaling laws for the bottlebrush backbone and side chains are determined through small‐angle neutron scattering analysis of a systematic series of poly(lactic acid) bottlebrush polymers synthesized via a “grafting‐through” ring‐opening polymerization. Scattering profiles are modeled with the empirical Guinier–Porod, rigid cylinder, and flexible cylinder models. Side chains are found to be only weakly stretched, with an end‐to‐end distance proportional to N0.55, while the overall bottlebrush increases in size proportional to N0.77. These results demonstrate that the bottlebrush backbone is not fully extended and that both side chains and backbone have significant conformational flexibility in solution. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 104–111 |
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| Keywords: | bottlebrush polymers poly(lactic acid) small‐angle neutron scattering |
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