Preparation of fluorescent waterborne polyurethane nanodispersion by high-gravity miniemulsion polymerization for multifunctional applications

Abstract

Polymer encapsulated fluorescent nanoparticles have found many applications in bioimaging, fluorescent gels and inks. However, their translation into the practical products has been slow because it is still difficult to produce nanoparticles that are consistent “batch-to-batch” for scale-up. Herein, we develop a high-gravity miniemulsion polymerization route for fluorescent waterborne polyurethane (PU) by using rotating packed bed (RPB) reactor for process intensification. In optimized conditions, the PU nanoparticles obtained exhibited an average size of 137 nm with narrow size distribution. Dispersion stability of the PU nanodispersions was investigated and no significant sediments or aggregates were observed for up to one month. The 1,1,2,3,4,5-hexaphenylsilole dyes, a kind of typical aggregation-induced emission luminogens (AIEgens), could be in situ loaded in PU nanoparticles, forming fluorescent nanodispersions of AIEgens@PU in aqueous solution. The preliminary applications of AIEgens@PU nanodispersion for in vitro fluorescent labeling of cells, transparent fluorescent films and anti-counterfeit printing inks were demonstrated. This study demonstrated that the newly developed high-gravity miniemulsion polymerization method provides an effective route to waterborne PU nanodispersion for multifunctional applications.