Solution-dispersed porous hyperbranched conjugated polymer nanoparticles for fluorescent sensing of TNT with enhanced sensitivity

Solution-dispersed porous hyperbranched conjugated polymer nanoparticles (PHCPN) were prepared via Suzuki polymerization in a toluene-in-water miniemulsion system. PHCPN with an average particle size of 40–120 nm can disperse in common organic solvents and show blue emission. PHCPN exhibit a much larger specific surface area (133 m2 g−1), compared with the analogues, hyperbranched conjugated polymer nanoparticles (HCPN, 13 m2 g−1) with octyl chains and a linear conjugated polymer (LCP, 0 m2 g−1). Moreover, PHCPN have enhanced sensitivity in both a THF dispersion and the solid state due to facile diffusion of TNT inside the porous conjugated polymer network structure. Especially, PHCPN-coated indicating papers can visually and reversibly detect trace TNT particulates with a low detection limit of 0.5 ng mm−2, which is about 20-fold more sensitive than that of the linear conjugated polymer (LCP).