Preparation Of Novel Conjugated Porous Polymer Nanoparticles For Sensing Application

2,4,6-Trinitrophenol（TNP）,as a common nitroaromatic explosive,is widely used in organic synthesis,mountain mining and military fields,which has brought great harm to the environment,personal and national property safety.Therefore,it is essential to realize an efficient detection of TNP.At present,there are many methods for the detection of trace TNP.Among them,the fluorescent sensing technology based on organic light-emitting materials has attracted the attention of researchers due to its advantages of high sensitivity,low cost,simple operation,etc.However,conventional organic fluorescent materials are hydrophobic,so it is still difficult to achieve an efficient detection of nitroaromatic compounds in aqueous phase.In this paper,combining the porosity of conjugated porous polymers and the dispersibility of nanoparticles,a series of uniformly dispersed conjugated porous polymer nanoparticles in water phase were prepared by Suzuki-miniemulsion polymerization method.The fluorescent sensing properties towards nitroaromatic compounds based on the conjugated porous polymers nanoparticles were investigated,and the fluorescent sensing mechanism were explored.The specific research contents are as follows:1.The conjugated porous polymer PSi An powder and nanoparticles were prepared by conventional Suzuki coupling method and Suzuki-miniemulsion polymerization method,respectively,with tetrakis（4-bromophenyl）silane and anthracene diboronic ester as monomers.The particle size of PSi An nanoparticles is 20–25 nm;compared with powder,PSi An nanoparticles possess a larger specific surface area of 157.23 m²g^-1;the nanoparticle characteristics and porosity are conducive to the adsorption and diffusion of analytes,and improve detection sensitivity.The limit of detection and limit of quantification of PSi An nanoparticles for pure aqueous TNP detection were 0.33μM and 1.11μM,respectively,and showed good selectivity towards TNP.The study of the sensing mechanism confirms that there may be photo-induced electron transfer,F?rster resonance energy transfer and inner filter effect during the detection of TNP.2.Two kinds of conjugated porous polymer P4Si F and P3Si F nanoparticles were prepared by Suzuki-miniemulsion polymerization with bromotetraphenylsilane with different linking sites and fluorene diboronic ester.The specific surface areas are respectively 101.8 m²g^-1 and 128.5 m²g^-1,and the pore diameters are all concentrated at 1.9 nm.The sensing performance of nitroaromatic explosives in aqueous phase was tested,and the quenching constants of P4Si F and P3Si F towards TNP were 6.43×10⁴M^-1 and 4.97×10⁴ M^-1,respectively.The study of the fluorescence sensing mechanism showed that the inner filter effect was the main reason for the high sensitivity and high selectivity of nitrophenols sensing based on the two polymer nanoparticles.The standard addition/recovery method was used to detect the TNP content in the actual water samples,and the recovery rates of TNP were between 95.06%–107.06%;the t-test showed that the fluorescence sensing method using P4Si F and P3Si F nanoparticles as sensing materials realized a sensitive and reliable detection of TNP in aqueous phase（95%confidence level）.3.Organic/inorganic hybrid nanomaterials have good water dispersibility.Three kinds of fluorescent silica microspheres PSN1–PSN3 were prepared via chemical modification of surface of vinyl silica microspheres with different ratios of vinyl tetraphenylethene monomers through free radical polymerization.The particle size of PSN1–PSN3 were ca.400 nm,and they could be uniformly dispersed in aqueous phase.Taking PSN1 as an example,the fluorescence sensing towards TNP in aqueous phase was carried out,with the quenching constant of 4.28×10⁴ M^-1 and the limit of detection of 0.31μM,showing high sensitivity and selectivity.The actual water sample test proves that a highly sensitive and reliable fluorescent sensing detection of TNP in aqueous phase was realized by the fluorescent silica microspheres.