Poly(acrylate) with a tetraphenylethene pendant with aggregation-induced emission (AIE) characteristics: highly stable AIE-active polymer nanoparticles for effective detection of nitro compounds

Acrylate monomers with aggregation-induced emission (AIE) attributes were prepared by reacting 4-(1,2,2-triphenylvinyl)phenol with 1-bromoalkan-1-ol, followed by the treatment with acryloyl chloride in the presence of a base. The resulting acrylate monomers were polymerized by free radical polymerization to give very high molecular-weight AIE-active polymers (400 000-650 000) with low polydispersity indices (1.28-1.51). Thermal stabilities of the AIE polymers are comparable to that of poly(methyl methacrylate) (PMMA), while their glass transition temperatures are 50-70 degrees C lower than that of PMMA. The AIE polymers are soluble in common organic solvents and have outstanding film-forming ability. Most importantly, the polymers in the mixtures of THF-H2O can form extremely stable nanoparticles, with no tendency towards agglomeration at 4 C for over nine months. The polymers exhibit much more significant AIE activity than their monomers and their precursor 4-(1,2,2-triphenylvinyl)phenol in THF-H2O mixtures. Fluorescence of the polymers in THF-H2O mixtures and in the film state can be dramatically quenched by a wide variety of nitro compounds, including picric acid, 2,4,6-trinitrotoluene, 2,4-dinitrotoluene, 4-nitrophenol, 4-nitrotoluene, nitromethane and nitrous sulfuric anhydride. The AIE polymers show no response to the reference compounds toluene and phenol. These AIE polymers are thus potential fluorescence sensors for nitroaromatic explosives.