Random packings have been studied using computer simulations for some time, but there is no agreement on the best way to obtain them, especially for nonspherical particles. The present work focuses on random packing of hard spherocylinders. Starting from the mechanical contraction method (Williams and Philipse. Phys. Rev. E 2003, 67, 051301), a modification is introduced that makes it easier to obtain reproducible values, by simplifying the selection of some parameters. Furthermore, it is found that the final packings can be compressed further using Monte Carlo style particle moves. Random packings were generated for a wide range of aspect ratios, 0 ≤ L/D ≤ 40, and it was verified that the final packings do not show positional nor orientational ordering. ■ INTRODUCTIONA random packing is, in a broad sense, a compact configuration in which the particles that form the system are disordered. Random packings of macroscopic objects can be obtained using simple experiments, by pouring, shaking, and compressing a container where such particles are held. This has been done for different particle shapes, and it has been found that for each kind of particle a reproducible value (within a certain range) can be obtained. 1−3 Because of this one might expect that colloidal suspensions and macroscopic particles of the same shape would give the same random packing volume fraction, but this does not always seem to happen. Sacanna et al. studied packing densities of ellipsoidal silica colloids for aspect ratios 1 ≤ α < 4.5 and compared these with simulation results. 4 They report slightly higher packing fractions than the values reported in simulations and no long-range positional or orientational order. Buitenhuis and Philipse studied the sedimentation of colloidal rods with aspect ratios α > 10 via centrifugation, and in this work the formation of ordered sediments was reported. 5 Another study also reported nematic order in sediments obtained using centrifugation of colloidal suspensions of rods with aspect ratios 3.6 ≤ α ≤ 8. 6 These results seem to indicate that for relatively high aspect ratios compact random configurations are not easy to obtain.There have been several attempts at a theoretical account of random packing, in particular for packings of hard spheres. The reproducibility of random packing (within a certain range depending on the limitations of the method used) and a formal definition of random packing have been investigated. Truskett et al. introduced the concept "maximally random jammed state" for spheres, defined as the configuration which maximizes disorder among all jammed hard-sphere arrangements and that have minimum values for a set of typical order parameters. 7 Kamien and Liu explained the random close packing density of spheres as a special well-defined divergent end point of a set of metastable branches of the pressure. 8 This concept could explain the reproducibility of such a value obtained using a wide variety of methods, including experiments as well as simulations. Chaikin et al. pointed out t...

We present a detailed numerical study of multi-component colloidal gels interacting sterically and obtained by arrested phase separation. Under deformation, we found that the interplay between the different intertwined networks is key. Increasing the number of component leads to softer solids that can accomodate progressively larger strain before yielding. The simulations highlight how this is the direct consequence of the purely repulsive interactions between the different components, which end up enhancing the linear response of the material. Our work provides new insight into mechanisms at play for controlling the material properties and open the road to new design principles for soft composite solids 0 a