Conjugated Microporous Polymer Nanoparticles that Disperse in Water for Detection of Nitroaromatics

The conjugated microporous polymer (CMP) PFSiBT nanoparticles were prepared via Suzuki-miniemulsion polymerization using benzothiadiazole diboronic ester and tetrabromofluorenylsilane as monomers. The nanoparticles exhibit a spherical particle morphology with a particle size of ca. 93.9 nm, and they could be uniformly dispersed in aqueous solution. The Brunauer–Emmett–Teller (BET) surface area of PFSiBT is 447 m2/g, with a microporous structure concentrated at a pore size of 0.86 nm. The nanoscale feature and porosity of the PFSiBT nanoparticles are conducive to the good dispersity in water and the adsorption/diffusion of the analytes, which facilitates the PL sensing toward nitroaromatics in aqueous media. In the fluorescence sensing experiments, the PFSiBT nanoparticles demonstrate a sensitive and selective detection toward 2,4,6-trinitrophenol (TNP) in aqueous solution, with a quenching constant of 3.53 × 104 M–1 and a detection limit of 0.71 μM, respectively, and good anti-interference characteristics against common ions were realized. The presence of TNP in real water samples was identified using the standard spike/recovery method, and the recovery percentage of TNP varied from 95.50 to 103.14% in different water samples. The t test data indicate that the fluorescence sensing method utilizing PFSiBT nanoparticles as the sensing material exhibits results comparable to those of the high-performance liquid chromatography (HPLC) method at a 95% confidence level.