Size- and charge-controllable polystyrene spheres for templates in the preparation of porous silica particles with tunable internal hole configurations

• Surfactant-free polystyrene spheres with controllable size and charge.
• Control of size (80–350 nm) by changing temperature and styrene amount.
• Control of charge (from −50 to +40 mV) by changing initiator concentration and type.
• The effectiveness of polystyrene for structurizing particles in the spray method.
• Control of hole cavity, internal structure, and external shape by polystyrene type.

Studies on the synthesis of polystyrene spheres have steadily increased in number. However, information regarding control of the physicochemical properties (i.e., size and charge) of polystyrene and its application as a template for the structure of materials remains limited. The purpose of our study was to synthesize surfactant-free polystyrene spheres with a controllable size (from 80 to 350 nm) and charge (from −50 to +40 mV) using a single-step and facile process, and to demonstrate their applications as templates for facilitating the production of porous particles with a tunable internal hole structure. Different from other polystyrene synthesis methods, the present synthesis procedure was conducted under surfactant-free conditions. To control polystyrene size and charge, several reaction parameters (i.e., temperature, styrene amount, and initiator concentration and type (cationic and anionic)) were investigated. To investigate the effectiveness of our synthesized polystyrene as a structure template, the synthesized polystyrene spheres were mixed with a host material and used in a spray method. As models of a host material, 15-nm silica nanoparticles and tetramethyl orthosilicate were used. These raw materials were selected because information about the exploitation of these materials remains limited. The results of the spray method showed that flexibility in the control of the size and surface charge of the polystyrene template made it possible to assist in the creation of particles with different hole configurations, including porous and hollow particles with control over the hole cavity, the internal structure, and the external shape. In addition, a theoretical explanation and a design for the mechanism of a hole-structured formation were also added, which would be important for the scaling-up prediction and estimation.

Figure optionsDownload as PowerPoint slide