In this combined experimental and simulation study, we utilize bond-order topology to quantitatively match particle volume fraction in mechanically uniformly compressed colloidal suspensions with temperature in atomistic simulations. The obtained mapping temperature is above the dynamical glass transition temperature, indicating that the colloidal systems examined are structurally most like simulated undercooled liquids. Furthermore, the structural mapping procedure offers a unifying framework for quantifying relaxation in arrested colloidal systems.
Roughening the surface of spherical colloids can drastically change their translational and rotational dynamics in dense suspensions. Using 3D confocal microscopy, we show that roughness not only lowers the concentration of the translational colloidal glass transition, but also generates a broad concentration range in which the rotational Brownian motion changes signature from high-amplitude diffusive to low-amplitude rattling. This hitherto not reported second glass transition for rough spherical colloids emerges when the particle intersurface distance becomes comparable to the roughness leng…
We describe a model for the colloidal glass transition that is based on Feynman's theory for the $λ$-transition in liquid helium. Our model essentially counts the number of configurations of dynamic loops, strings or clusters of different sizes, and determines the glass transition volume fraction $ϕ_{g}$ from the distribution of these heterogeneities. Since confinement restricts the available number of configurations for these loops, strings and clusters, its effect on $ϕ_{g}$ can also be calculated in a relatively straightforward manner.
We use an analogue of nanoindentation on a colloidal glass to elucidate the incipient plastic deformation of glasses. By tracking the motion of the individual particles in three dimensions, we visualize the strain field and glass structure during the emerging deformation. At the onset of flow, we observe a power-law distribution of strain indicating strongly correlated deformation, and reflecting a critical state of the glass. At later stages, the strain acquires a Gaussian distribution, indicating that plastic events become uncorrelated. Investigation of the glass structure using both static …
We study experimentally the origin of heterogeneous dynamics in strongly driven glass-forming systems. Thereto, we apply a well-defined force with a laser line trap on individual colloidal polystyrene probe particles seeded in an emulsion glass composed of droplets of the same size. Fluid and glass states can be probed. We monitor the trajectories of the probe and measure displacements and their distributions. Our experiments reveal intermittent dynamics around a depinning transition at a threshold force. For smaller forces, linear response connects mean displacement and quiescent mean squared…
Dynamic Light Scattering (DLS) measurements were performed on colloidal suspensions of Laponite\textsuperscript{\textregistered} at different concentrations in the range $C_\text{w}= (1.5÷3.0)$%. The slowing down of the dynamics induced by aging was monitored by following the temporal evolution of autocorrelation functions at different concentrations towards the gel and glass transition. Exploiting analogies with supercooled liquids approaching their glass transitions, an Angell plot for the structural relaxation times was drawn. Finally, the fragility of Laponite\textsuperscript{\textregister…
We explore the glassy dynamics of soft colloids using microgels and charged particles interacting by steric and screened Coulomb interactions, respectively. In the supercooled regime, the structural relaxation time $τ_α$ of both systems grows steeply with volume fraction, reminiscent of the behavior of colloidal hard spheres. Computer simulations confirm that the growth of $τ_α$ on approaching the glass transition is independent of particle softness. By contrast, softness becomes relevant at very large packing fractions when the system falls out of equilibrium. In this non-equilibrium regime, …
Glass is a liquid that has lost its ability to flow. Why this particular substance undergoes its dramatic slowing down in kinetics while remaining barely distinguishable in structure from the fluid state upon cooling constitutes the central question of glass transition physics. Here, we experimentally tested the pathway of kinetic slowing down in glass$\textrm{-}$forming liquids that consisted of ellipsoidal or binary spherical colloids. In contrast to rotational motion, the exponential scaling between diffusion coefficient and excess entropy in translational motion was revealed to break down …
Dynamics in Colloidal Liquids near a Crossing of Glass- and Gel-Transition Lines
在模式耦合理论的理想玻璃化转变，均方位移和关联函数的密度波动的胶体液体的颗粒相互作用与一个方阱势的状态附近的交叉线的过渡到凝胶与线的过渡到玻璃。它演示了如何动态是由逮捕的机制，由于硬核排斥和由于吸引诱导键的形成，以及由附近的高阶玻璃化转变奇点的相互作用统治。玻璃化转变奇异点附近的慢动力学的普遍松弛定律的应用解释了计算的均方位移的时间依赖性的定性特征，这与Zaccarelli等人在分子动力学模拟研究中获得的结果是一致的。等人[Phys.Rev.E66，041402（2002）]。关联函数发现的光子相关光谱在胶束系统的Mallamace等。[Phys. Rev. Lett. 84，5431 2000）]可以定性地解释为从凝胶到玻璃动力学的交叉。
We developed a generalized replicated liquid theory for glassy phases of non-spherical uniaxial molecules and colloids, which becomes exact in the large dimensional limit $d\to\infty$. We then applied the scheme to patchy colloids with sticky patches at their heads and tails. The system exhibits rich phase behaviors involving the translational and orientational degrees of freedom. We found a novel glass-glass transition between glasses with large/small orientational fluctuations.
