AI 中文总结
研究双峰胶体凝胶，发现中等尺寸差异下粒子尺寸对其结构尺度和力学响应的控制作用强于局部堆积。
AI 中文摘要
胶体凝胶常被建模为单分散粒子网络，但实际配方通常包含多种特征尺寸的粒子。本文采用流体动力学解析的大规模胶体耗尽凝胶模拟，研究大小比为1:2的双峰体系中粒子尺寸和局部堆积的影响。增大大粒子分数会引入新的异型角基序，显著增加参与四面体结构的键比例，在中等组成时达到最大值；但这些额外的刚性基序不会重组为更大或连接性更强的四面体聚集体，平均配位数和特征聚集体尺寸几乎与组成无关。相比之下，随着大粒子分数增加，空隙和聚集体尺寸分布会系统地粗化；当以与组成相关的粒子长度尺度归一化时，这些介观尺度分布基本重合，表明组成变化主要是重新缩放凝胶结构，而非产生不同的刚性网络拓扑结构。采用柯西-玻恩理论估算的弹性模量，与该有效长度尺度的契合度高于局部四面体基序的丰度。结果表明，对于中等尺寸差异，粒子尺寸对双峰胶体凝胶的结构尺度和预测力学响应的控制作用，强于增强的局部堆积。
英文摘要
Colloidal gels are frequently modeled as monodisperse particle networks, although practical formulations commonly contain particles with multiple characteristic sizes. Here, we use large-scale, hydrodynamically resolved simulations of colloidal depletion gels to isolate the effects of particle size and local packing in bimodal systems with a small-to-large size ratio of 1:2. Increasing the large-particle fraction introduces new heterotypic angular motifs and substantially increases the fraction of bonds participating in tetrahedral structures, with a maximum at intermediate composition. However, these additional rigid motifs do not reorganize into larger or more highly connected tetrahedral aggregates. The mean coordination and characteristic aggregate size remain nearly composition independent. By contrast, the void and cluster-size distributions coarsen systematically as the large-particle fraction increases. These mesoscale distributions largely collapse when normalized by a composition-dependent particle length scale, indicating that changes in composition primarily rescale gel architecture rather than producing distinct rigid-network topologies. An elastic modulus estimated using Cauchy-Born theory similarly follows this effective length scale more closely than the abundance of local tetrahedral motifs. These results show that, for moderate size disparity, particle size controls the structural scale and predicted mechanical response of bimodal colloidal gels more strongly than enhanced local packing.
