Core-Shell SiO2-PS Colloids with Controlled Eccentric Ratio.

Precisely controlling microstructure of colloidal particles is crucial for their applications. Core-shell colloids have been extensively synthesized and used in past decades. However, controlling the location of cores in core-shell particles remains a challenge. To address this problem we explored the synthesis of SiO2-PS core-shell colloids by using a simple system containing only core particles, monomer, initiator, and water/ethanol and found the increase of ethanol/water ratio can induce a structure transition sequence from eccentric to concentric to eccentric to concentric to eccentric. Furthermore, we illustrate that the eccentric ratios of SiO2-PS core-shell colloids, that is, the location of SiO2 cores in the whole particles, can be precisely controlled by a two-step polymerization procedure. It is anticipated that our results can widen the application of core-shell colloids, especially after the introduction of functionality for core or shell materials.