Solvent-Assisted Reshaping of Multicomponent Colloids

Advances in phase separation techniques and micro- and nanoscale fabrication have led to a surge in the popularity and relevance of anisotropic colloids. Due to their asymmetric properties, these colloids show great promise as advanced materials, including solid surfactants, micromotors, and hydrophobic coatings. To further broaden and enhance the applicability of these systems, researchers need to develop new, highly tunable synthesis and fabrication techniques. We present a novel method utilizing the technique of solvent assisted phase separation (SAPS), which is traditionally used on non-crosslinked, biphasic polymer particles to promote complete phase separation. We discovered that when SAPS is performed on partially cross-linked particles with a kinetically-arrested structure, the particle components rearrange to create a new morphology. This technique enables the creation of particles with sharply contrasting surface structures, and a model system is presented showcasing anisotropic surface roughness. We propose a mechanism for the process, highlighting the dependence on the relative amphiphilicities and interfacial tensions of present phases. A potential application of the model system as a reversible solid surfactant is also showcased, along with a demonstration of morphology tunability.