The Impact of Nonpolymerizable Swelling Agents On The Synthesis of Particles With Combined Geometric, Interfacial, and Compositional Anisotropy.

Abstract

Seeded emulsion polymerization is by far the most successful synthetic method for making anisotropic particles with precise control and high throughput. However, this synthesis involves multiple steps and the types of anisotropic properties that have been made on particles are limited. Here, we demonstrate, by using two different types of nonpolymerizable swelling agents, that we can simplify this method while still producing colloidal dimers with combined anisotropic properties in geometry, interface, and composition. When we swell cross-linked polystyrene seed particles with a simple solvent toluene, without additional polymerization steps we can make dimers with asymmetric distribution of surface charges and roughness on two lobes by fast extraction of toluene. We further show that this toluene-swelling-extraction method can promote the surface modification of the second lobe selectively especially for hydrophilic and stimuli-responsive polymers, which was a significant challenge in dimer synthesis. When we change the swelling agent to a sol-gel precursor, that is, tetraethyl orthosilicate, we can make polystyrene-silica hybrid particles with different morphologies. Our method provides a facile synthetic platform for making colloidal particles with different types of anisotropic properties, which are expected to find important applications for colloidal surfactant, self-assembly, and artificial motors.