Colloidal Recycling: Reconfiguration of Random Aggregates into Patchy Particles

Abstract

The key ingredients to the successful bottom-up construction of complex materials are believed to be colloids with anisotropic shapes and directional, or patchy, interactions. We present an approach for creating such anisotropic patchy particles based on reconfiguring randomly shaped aggregates of colloidal spheres. While colloidal aggregates are often undesirable in colloidal dispersions due to their random shapes, we exploit them as a starting point to synthesize patchy particles. By a deliberate destabilization of the colloidal particles, diffusion-limited aggregation is induced which partitions the particles into randomly shaped aggregates with controlled size distribution. We achieve a reconfiguration of the aggregates into uniform structures by swelling the polymer spheres with an apolar solvent. The swelling lowers the attractive van der Waals forces, lubricates the contact area between the spheres, and drives the reorganization through minimization of the interfacial energy of the swollen polymer network. This reorganization process yields patchy particles whose patch arrangement is uniform for up to five patches. For particles with more patches, we find that the patch orientation depends on the degree of phase separation between the spheres and the monomer. This enables the synthesis of patchy particles with unprecedented patch arrangements. We demonstrate the broad applicability of this recycling strategy for making patchy particles as well as clusters of spheres by varying the swelling ratio, swelling solvent, surfactant concentration, and swelling time.

Nonisotropic Self‐Assembly of Nanoparticles: From Compact Packing to Functional Aggregates

“…Thus, mixtures of patchy microparticles were obtained by sonication of oil-in-water emulsions stabilized with negatively-charged PS particles and subsequent photopolymerization of the oil [216]. Other mixtures were produced through the assembly of polymer particles bearing a liquid protrusion and the subsequent polymerization of the liquid [217,218]. The direct confinement in droplets, initially developed by Lauga et al [219], was largely exploited by Pine and coworkers [56,[220][221][222][223], in particular with 540 nm amidinated cross-linked PS spheres.…”

Percolation in binary and ternary mixtures of patchy colloids

“…Patchy colloids are excellent candidates to design new materials with properties on-demand by controlling the microscopic details of the interparticle interaction. The distribution, number, and types of patches can be tuned [1][2][3][4] such that patchy colloids self-assemble into new structures that are not found in isotropically interacting colloids. Examples are the directed self-assembly of patchy colloids into a kagome lattice 5 , polyhedra 6 , and micelles 7 .…”

Complex patchy colloids shaped from deformable seed particles through capillary interactions

“…The colloidal recycling method We studied the shape and assembly pathway of patchy particles constructed from spheres of varying rigidity. These patchy colloids were obtained by applying the colloidal recycling method, 26 illustrated in Fig. 1A, to spheres with different crosslink densities.…”

“…4 We have recently contributed to the available synthetic approaches with a strategy based on reconfiguring random aggregates of spheres into patchy particles. 26 The technique relies on the introduction of apolar droplets to the contact areas of the aggregated spheres dispersed in aqueous solution. These droplets enable rotational mobility and induce a reorganization of the spheres driven by capillary forces.…”