Preparation of fluorescent polystyrene microspheres by improving swelling performance based on molecular weight and surface carboxyl group content

The fluorescent microspheres are prepared by the swelling-evaporation method. The optimal swelling conditions are obtained by researching related factors, such as types and dosages of swelling agent, dosages of fluorescent substance, swelling time and swelling temperature. Considering that the structure of microspheres can influence the swelling properties, the paper mainly focuses on the effect of molecular weight and surface carboxyl group content of polystyrene microspheres on swelling properties. When the molecular weight of microspheres is 75276 g mol^-1, the density of carboxyl group on their surface is 6.94×10^-4 mol g^-1, and the doping amount of europium complex reaches the maximum of 24.9 mg g^-1 with the strongest fluorescence intensity. Meanwhile, the as-prepared fluorescent microspheres have high monodispersity, uniform particles size and high thermal stability (the decomposition temperature is 385^oC), which sets up the good foundation for biomolecule detection. So, this work provides a significant experience for the preparation of fluorescent microspheres.

Keywords:
swelling method; fluorescence intensity; optimal conditions; doping of europium complex