Narrowly Distributed Hollow Polystyrene Microspheres with Controllable Size and High Light-Blocking Performance for Waterborne Coatings Applications

The aesthetics of buildings can be increased by adding titanium dioxide to improve the covering of architectural coatings but the poor compatibility of titanium dioxide with organic resins adversely affects the formation, adhesion, and stability of coatings. Therefore, developing covering agents with high light-blocking performance, low cost, and excellent properties is important for advanced construction. Herein, hollow polystyrene microspheres (size around 490 nm) were synthesized by combining seed emulsion polymerization with alkali swelling technology for use in waterborne coatings to substitute titanium dioxide and enhance the whiteness and coverage performance of coatings. The influence of the emulsifier concentration on microsphere size was investigated along with the factors affecting the volume expansion rate of microspheres. Hollow microspheres with good volume expansion rates were then selected as covering agents to enhance the light-blocking performance of waterborne coatings. The results revealed that the core latex particle size can be controlled between 150 and 400 nm by adjusting the content of sodium dodecyl sulfate (SDS). The volume expansion rate of the microspheres after swelling by alkali solution reached up to 57 %. The transmittance of thin films prepared by mixing the hollow polystyrene microspheres with water-based coatings at a 1:4 ratio reached as low as 47.9 %. Compared to titanium dioxide, the as-fabricated hollow polystyrene microspheres exhibited better compatibility with water-based coatings combined with good cost-effectiveness, making them promising as a green covering agent meeting various market demands.