Colloidal gels result from the aggregation of Brownian particles suspended in a solvent. Gelation is induced by attractive interactions between individual particles that drive the formation of clusters, which in turn aggregate to form a space-spanning structure. We study this process in aluminosilicate colloidal gels through time-resolved structural and mechanical spectroscopy. Using the time–connectivity superposition principle a series of rapidly acquired linear viscoelastic spectra, measured throughout the gelation process by applying an exponential chirp protocol, are rescaled onto a universal master curve that spans over eight orders of magnitude in reduced frequency. This analysis reveals that the underlying relaxation time spectrum of the colloidal gel is symmetric in time with power-law tails characterized by a single exponent that is set at the gel point. The microstructural mechanical network has a dual character; at short length scales and fast times it appears glassy, whereas at longer times and larger scales it is gel-like. These results can be captured by a simple three-parameter constitutive model and demonstrate that the microstructure of a mature colloidal gel bears the residual skeleton of the original sample-spanning network that is created at the gel point. Our conclusions are confirmed by applying the same technique to another well-known colloidal gel system composed of attractive silica nanoparticles. The results illustrate the power of the time–connectivity superposition principle for this class of soft glassy materials and provide a compact description for the dichotomous viscoelastic nature of weak colloidal gels.

胶体凝胶由悬浮在溶剂中的布朗粒子聚集而成。凝胶化是由单个粒子之间的吸引力相互作用引起的，这些相互作用驱动簇的形成，而簇又聚集形成一个跨空间的结构。我们通过时间分辨结构和机械光谱研究了铝硅酸盐胶体凝胶中的这一过程。使用时间-连通性叠加原理，在整个凝胶过程中通过应用指数啁啾协议测量的一系列快速获得的线性粘弹性光谱被重新缩放到通用主曲线上，该曲线以降低的频率跨越八个数量级。该分析表明，胶体凝胶的基本弛豫时间谱在时间上是对称的，幂律尾部的特征是在凝胶点设置的单个指数。微观结构的机械网络具有双重性；在短的尺度和快速的时间，它看起来像玻璃一样，而在更长的时间和更大的尺度，它是凝胶状的。这些结果可以通过简单的三参数本构模型捕获，并证明成熟胶体凝胶的微观结构具有在凝胶点创建的原始样品跨越网络的残余骨架。我们的结论通过将相同的技术应用于另一个众所周知的由有吸引力的二氧化硅纳米粒子组成的胶体凝胶系统得到证实。