Partial structural order of gel-forming material detected as multimodal subdiffusion by logarithmic measure
Partial structural order of gel-forming material detected as multimodal subdiffusion by logarithmic measure
复制标题
DOI：
10.1088/1361-648x/ac1cb1
复制
发表时间：
2021-11-10
影响因子：
2.7
通讯作者：
Hanasaki, Itsuo
中科院分区：
文献类型：
--
作者：
Shimizu, Yugo;Hanasaki, Itsuo
当组分之间的结合位点达到足够的数密度时，悬浮在液体中的纤维状纳米材料形成凝胶结构。纤维素纳米纤维（CNF）是这样的纳米材料之一，并且透明纸通过干燥其水性分散体来制造。因此，重要的是表征湿状态，但特异性荧光标记分子不可用于任意CNF。本文提出了一种基于布朗探测粒子的单粒子跟踪方法。我们专注于布朗运动的不均匀性，以检测溶胶和凝胶之间的部分结构顺序，这是不平凡的特征。扩散行为的简单对数测量揭示了布朗运动的多峰性质取决于CNF浓度。仅由整体均方位移的次扩散行为并不能说明它是由CNFs在局部环境中的限制引起的，还是由可能在分散体中扩散的单个CNFs结合引起的。然而，颗粒大小的依赖性澄清，它不是由约束，但约束效应。此外，对数测量方法能够通过头部而不是尾部检测重叠分布。用一种简单的方法通过体系的流变非均匀性来检测部分结构有序性，将有助于对凝胶形成材料的进一步理解。
Fibrous nanomaterials suspended in liquid form gel structures when the binding sites between the components reach sufficient number densities. Cellulose nanofibers (CNFs) are one of such nanomaterials, and transparent papers are fabricated by drying their aqueous dispersions. It is therefore important to characterize the wet state, but the specific fluorescent marker molecules are not available for arbitrary CNFs. We report an approach based on the single particle tracking of Brownian probe particles. We focus on the nonuniformity in the Brownian motion to detect the partial structural order between sol and gel, which is nontrivial to characterize. The simple logarithmic measure of diffusive behavior reveals the multimodal nature of Brownian motion depending on the CNF concentration. The subdiffusive behavior by the overall mean squared displacements alone does not tell whether it is caused by confinement in the local environment by CNFs, or binding to single CNFs possibly diffusing in the dispersion. However, the particle-size dependence clarifies that it is not caused by binding but the confinement effect. Furthermore, the logarithmic measure approach enables the detection of overlapping distributions through their heads rather than tails. The detection of partial structural order by rheological non-uniformity of the system with a simple approach will contribute to the further understanding of gel forming materials in general.