Musino Dafne, Oberdisse Julian, Farago Bela, Alegria Angel, Genix Anne-Caroline
Laboratoire Charles Coulomb (L2C), Université de Montpellier, CNRS, F-34095 Montpellier, France.
Institut Max von Laue-Paul Langevin (ILL), 71 Avenue des Martyrs, CS 20156, F-38042 Cedex 9 Grenoble, France.
ACS Macro Lett. 2020 Jun 16;9(6):910-916. doi: 10.1021/acsmacrolett.0c00369. Epub 2020 Jun 4.
The segmental dynamics of styrene-butadiene nanocomposites with embedded silica nanoparticles (NPs, ca. 20 vol. %) has been studied by broadband dielectric (BDS) and neutron spin-echo spectroscopy (NSE). It is shown by BDS that overlapping contributions only allow us to conclude on a range of distributions of relaxation times in simplified industrial nanocomposites formed with highly polydisperse NPs. For comparison, structurally similar but less aggregated colloidal nanocomposites have a well-defined distribution of relaxation times due to the reduced influence of interfacial polarization processes. This distribution is widened with respect to the neat polymer, without change in the position of the maximum and at most a small slowing down visible in the average time. We then demonstrate that incoherent NSE can be used to resolve small modifications of segmental dynamics of the industrial samples. By carefully choosing the q-vector of the measurement, experiments with fully hydrogenated polymer give access to the self-dynamics of the polymer in the presence of silica on the scale of approximately 1 nm. Our high-resolution measurements show that the segmental motion is slightly but systematically slowed also by the presence of the industrial filler NPs.
采用宽带介电谱（BDS）和中子自旋回波光谱（NSE）研究了含有二氧化硅纳米粒子（NPs，约20体积%）的丁苯纳米复合材料的链段动力学。BDS结果表明，在由高度多分散的NPs形成的简化工业纳米复合材料中，重叠贡献仅使我们能够推断出弛豫时间的分布范围。相比之下，由于界面极化过程的影响减小，结构相似但聚集程度较低的胶体纳米复合材料具有明确的弛豫时间分布。相对于纯聚合物，这种分布变宽，最大值位置不变，平均时间最多有轻微减慢。然后我们证明，非相干NSE可用于解析工业样品链段动力学的微小变化。通过仔细选择测量的q矢量，对完全氢化聚合物进行的实验能够在约1nm尺度上获得聚合物在二氧化硅存在下的自动力学。我们的高分辨率测量表明，工业填料NPs的存在也会使链段运动略有但系统性地减慢。
