Engineering the Surface Pattern of Microparticles: From Raspberry-like to Golf Ball-like.

Control of the shape and uniformity of colloid particles is essential for realizing their functionality in various applications. Herein, we report a facile approach for the synthesis of narrowly dispersed anisotropic microparticles with well-defined raspberry-like and golf ball-like surface patterns. First, we demonstrate that hybrid raspberry-like particles can be achieved through a one-pot polymerization method using glycidyl polyhedral oligomeric silsesquioxane (GPOSS) and pentaerythritol tetra(3-mercaptopropionate) (PETMP) as monomers. Varying the polymerization parameters such as catalyst loading, monomer concentration, and the molar ratio of monomers, we are able to regulate the sizes and surface protrusion numbers of these raspberry-like microparticles. The formation mechanism is attributed to a competition balance between thiol-epoxy reaction and thiol-thiol coupling reaction. The former promotes rapid formation of large core particles between PETMP and GPOSS droplets (which can serve as core particles), while the latter allows for generation of surface protrusions by PETMP self-polymerization, leading to the formation of raspberry-like surface patterns. Based on the different POSS contents in the surface protrusions and cores of the raspberry-like microparticles, we demonstrate that they can be used as precursors to produce microporous silica (sub)microparticles with golf ball-like morphology pyrolysis subsequently. Overall, this work provides a facile yet controllable approach to synthesize narrowly dispersed anisotropic microparticles with diverse surface patterns.