Preparation Of Fluorescent Conjugated Polymer Nanofiber Membranes By Electrostatic Spinning Research On Its Sensing Performance

World peace,people living and working in peace and a friendly environment are the common aspirations of all people.Therefore,people have been paying high attention to the use and detection of explosives.It is urgent to develop a sensitive,portable and efficient real-time detection system for explosives.The main components of explosives are nitroaromatic compounds,and its micro trace detection is very difficult.Gen-eral detection methods have limitations and are difficult to be widely used.Compared with other detection technologies,fluorescence sensing method has the following advantages in detection:high sensitivity,short response time,low cost,convenient device manufacture,simple operation,easy to carry,etc.,which has become the current research hotspot.Compared with other fluorescence sensing materials,fluorescence conjugated polymers have a multi-plier effect on the sensitivity of nitroaromatics due to the"molecular wire effect".At the same time,with the help of electrospinning technology,a thin film sensor with large specific surface area,high porosity,high permeability and controllable shape is prepared,which increases the contact opportunity between the nitroar-omatic hydrocarbons in the sensor materials,and effectively improves the sensitivity of the sensor to detect explosives in the water phase.In this paper,a series of fluorescent conjugated polymers of thiophene and phenyl polyfluorene with similar structures were designed and synthesized,and the sensors were prepared to explore the sensing performance of explosives in the aqueous phase.The specific research contents are as follows:1.Based on the relationship between the structure and properties of the fluorescent sensing materials,the fluorescent polymers were designed.By using the palladium-catalyzed Suzuki coupling reaction,five kinds of new fluorescent conjugated polymers containing thiophene and phenyl polyfluorene with similar structures were designed and synthesized:P（p-TPE-FO）,P（o-TPE-FO）,P（o-TPE-Cz）,P（DTDPE-FO）and P（COTh-FO）were characterized.The results show that the surface morphology of these five polymers is different,but they all have high thermal stability,specific photophysical properties,and high molecular weight.2.The aggregation-induced luminescence properties of P（p-TPE-Fo）,P（o-TPE-FO）,P（o-TPE-Cz）,P（DTDPE-FO）and P（COTh-FO）polymers in the mixed solution of THF/H₂O were studied.The results show that P（p-TPE-FO）,P（o-TPE-FO）,P（o-TPE-Cz）,P（DTDPE-FO）and P（COTh-FO）have the strongest aggre-gation induced luminescence properties when the water phase proportion is 95%,95%,98%,95%and 95%,respectively.Next,the fluorescence sensing performance of each polymer on different concentrations of tri-nitrophenol（TNP）,1,4-dinitrobenzene（DNB）and p-nitrotoluene（PNT）in aqueous phase was studied when the corresponding aggregation-induced luminescence effect was strongest.The results showed that the five polymers have the weakest detection capability for PNT and higher detection capability for DNB than TNP,P（DTDPE-FO）and P（COTh-FO）are less sensitive to three nitroaromatic compounds than P（p-TPE-Fo）,P（o-TPE-FO）and P（o-TPE-Cz）.Dynamic light scattering method was used to measure the particle size of the five polymer solutions at the highest fluorescence intensity The particle size were evenly distributed in the size range of 100 nm or below,which well proved the aggregation induced luminescence effect of the polymer.3.The electrospinning technology is used to doping P（p-TPE-FO）,P（o-TPE-FO）,P（o-TPE-Cz）,P（DTDPE-FO）into polystyrene（PS）for spinning.The receiving time of each polymer spinning is as follows:1 min,3 min,5 min,7 min and 9 min,so each polymer has obtained five different thickness,different fluo-rescence intensity electrostatic spinning film sensor.The fluorescence sensing performance of thin film sen-sor in aqueous solution containing TNP concentration of 10^-14 g/L¹0^-4 g/L was studied.The results show that P（p-TPE-FO）/PS,P（o-TPE-FO）/PS,P（o-TPE-Cz）/PS and P（DTDPE-FO）/PS have the best detection per-formance when the receiving time is 3 min,3 min,3 min and 5 min,respectively.Among them,P（DTDPE-FO）/PS showed the highest sensitivity to TNP in aqueous phase and the best detection performance.