Materials Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899.
Materials Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD 20899
Proc Natl Acad Sci U S A. 2020 Mar 10;117(10):5168-5175. doi: 10.1073/pnas.1916362117. Epub 2020 Feb 24.
Uncharged bottlebrush polymer melts and highly charged polyelectrolytes in solution exhibit correlation peaks in scattering measurements and simulations. Given the striking superficial similarities of these scattering features, there may be a deeper structural interrelationship in these chemically different classes of materials. Correspondingly, we constructed a library of isotopically labeled bottlebrush molecules and measured the bottlebrush correlation peak position [Formula: see text] by neutron scattering and in simulations. We find that the correlation length scales with the backbone concentration, [Formula: see text], in striking accord with the scaling of ξ with polymer concentration in semidilute polyelectrolyte solutions [Formula: see text] The bottlebrush correlation peak broadens with decreasing grafting density, similar to increasing salt concentration in polyelectrolyte solutions. ξ also scales with sidechain length to a power in the range of 0.35-0.44, suggesting that the sidechains are relatively collapsed in comparison to the bristlelike configurations often imagined for bottlebrush polymers.
未带电的瓶刷聚合物熔体和带电的聚电解质在溶液中表现出散射测量和模拟中的相关峰。鉴于这些散射特征的惊人表面相似性，这些在化学上不同的材料类别之间可能存在更深层次的结构相互关系。相应地，我们构建了一系列同位素标记的瓶刷分子库，并通过中子散射和模拟测量了瓶刷相关峰的位置 [公式：见正文]。我们发现相关长度与主链浓度成比例，[公式：见正文]，与半浓聚电解质溶液中聚合物浓度 [公式：见正文]的标度一致。在瓶刷相关峰中，随着接枝密度的降低而变宽，类似于聚电解质溶液中盐浓度的增加。ξ 也与侧链长度成比例，范围在 0.35-0.44 之间，这表明与通常想象的瓶刷聚合物的刷毛状构象相比，侧链相对塌陷。
