近日，美国乔治城大学的Emanuela Del Gado课题组与麻省理工学院的Gareth H.McKinley等人合作并取得一项新进展，他们成功发现了软颗粒凝胶隐藏的层级性。相关研究成果已于2023年5月4日在国际知名学术期刊《自然—物理学》上发表。

该研究团队揭示了一个隐藏的分形元素分层组织，控制粘弹性谱，并与固体矩阵拓扑的空间异质性相关联。这些分形元素构成了一个粘弹性主曲线的基础，通过使用模型凝胶的大规模三维微观模拟来构建。递归流变阶梯模型可以描述一系列颗粒体积分数和凝胶化速率。分形元素的层次结构提供了预测这些复杂材料的凝胶弹性和线性粘弹性响应所需的缺失普遍框架。

据悉，软颗粒凝胶由少量颗粒物质分散在连续的流体相中组成。尽管固体组分是少数成分，但它们组装成了多孔的矩阵，提供了刚度和机械响应的控制。流变响应和凝胶弹性是颗粒体积分数的直接函数。然而，不同实验报道的功能依赖的多样性为确定普遍定标律带来了挑战。

附：英文原文

Title: The hidden hierarchical nature of soft particulate gels

Author: Bantawa, Minaspi, Keshavarz, Bavand, Geri, Michela, Bouzid, Mehdi, Divoux, Thibaut, McKinley, Gareth H., Del Gado, Emanuela

Issue&Volume: 2023-05-04

Abstract: Soft particulate gels are composed of a small amount of particulate matter dispersed in a continuous fluid phase. The solid components assemble to form a porous matrix, providing rigidity and control of the mechanical response, despite being the minority constituent. The rheological response and gel elasticity are direct functions of the particle volume fraction. However, the diverse range of different functional dependencies reported experimentally has challenged efforts to identify general scaling laws. Here we reveal a hidden hierarchical organization of fractal elements that controls the viscoelastic spectrum, and which is associated with the spatial heterogeneity of the solid matrix topology. The fractal elements form the foundations of a viscoelastic master curve, constructed using large-scale three-dimensional (3D) microscopic simulations of model gels, which can be described by a recursive rheological ladder model over a range of particle volume fractions and gelation rates. The hierarchy of the fractal elements provides the missing general framework required to predict the gel elasticity and the linear viscoelastic response of these complex materials.

DOI: 10.1038/s41567-023-01988-7

Source: https://www.nature.com/articles/s41567-023-01988-7