Colloidal particle shape matters: Emulsion-directed shape design, interfacial mechanisms, and applications

Shape-controlled micro- and nanoparticles with tailored morphologies, microstructures, and dimensions exhibit distinct interfacial behaviors and functionalities in a wide range of colloid and interface-related processes. To rationally design such particles for targeted applications, it is essential to understand both the synthetic strategies for controlling particle shape and the mechanisms by which shape regulates interfacial phenomena. This review summarizes recent progress in emulsion-directed routes for shaping organic, inorganic, and hybrid colloidal particles by employing oil-water interfaces as dynamic reaction platforms. It highlights how emulsion type, composition, and flow/mixing conditions govern droplet structure, reaction pathways, and ultimately particle morphology. Particular emphasis is placed on the role of particle shape in dictating interfacial adsorption, orientation, packing states, and multiscale interaction mechanisms, including particle-particle, particle-interface, and particle-fluid coupling. On this basis, mechanistic correlations are established between shape-dependent interfacial behaviors and performance in representative applications such as Pickering emulsification, drug delivery, environmental remediation, and microwave absorption. A unifying picture is further proposed in which particle shape sets the physicochemical states of surfaces and surrounding fluid environments, thereby modulating positioning, adhesion dynamics, and mechanical action; these feedbacks in turn reshape interfacial activity and guide particle evolution, forming a self-reinforcing loop between construction and function. This review also highlights the limitations and outstanding challenges in achieving precise, scalable, and sustainable shape control, and outlines opportunities where advanced characterization, theory, simulation, and data-driven approaches could accelerate the interfacial design of shape-engineered particles for emerging industrial and engineering applications.