Preparation Of Aggregation-Induced Emission Molecule Doped Polymer And Its Glass Transition Temperature Test

After the concept of Aggregation Induced Emission(AIE)was proposed,research related to the nature of AIE sprang up.Therefore,AIE molecules can broaden the field of fluorescence detection in the state of solid-state aggregation.Tetraphenylethylene is one of the typical representatives of aggregation-induced emission molecules.It has a simple molecular structure and is very easy to functionalize,that is,it can been chemically modified to obtain a series of tetraphenylethylene derivative molecules with different functions,thereby widening the application of this class of molecules in various fields.Glass transition temperature(Tg)is one of the important property parameters of polymer materials.It directly determines the temperature range of application of polymer materials in the engineering field.At present,methods commonly used to measure Tg include:dilatometer method,dynamic thermomechanical analysis method,and differential scanning calorimetry.These detection methods have their own advantages and disadvantages.Therefore,seeking a more convenient and simple detection method has become a meaningful work.In recent years,people have used a simple blending doping method to AIE molecules and the polymer,and estimate the Tg by testing the inflection point of the fluorescence intensity with the temperature curve.In this paper,three kinds of AIE molecules with different melting points were been obtained by chemically modifying tetraphenylethylene molecules and introducing different substituents.Then,the polymer was prepared by the doping method of blending and copolymerization,and the difference of the Tg of the polymer by the two methods was compared.The basic rule of measuring the Tg of the polymer using AIE molecules was recognized.The specific research contents and staged results are as follows:1.Three tetraphenylethylene derivatives with different melting points were been synthesized.The polystyrene was been swollen by tetrahydrofuran and then simply blended with the three AIE molecules.The fluorescence intensity of the sample was been measured by a fluorescence spectrometer.The temperature corresponding to the sudden change of the fluorescence intensity was considered to be the glass transition temperature.Compared with the Tg value of the DSC test,it is found that when the melting point of the AIE molecule is lower than the Tg of the polystyrene,the Tg value of the fluorescence test deviates greatly from the true value.However,when the melting point of the AIE molecule is high,the bulk Tg of polystyrene is reduced to a small extent.On the other hand,comparing the Tg values of the two doping methods of blending and copolymerization.We found that the sample was obtained by copolymerization using AIE molecules with lower melting point,and the Tg of polystyrene can be detected more accurately(compared with DSC results).In addition,by mixing the two AIE molecules with different melting points and PMMA,it is also possible to test the Tg by the fluorescence method,but the deviation from the DSC test value is relatively large.It can be seen from the above results that the Tg of polymers are detected by using the AIE molecule,it is necessary to consider the structure of the AIE molecule,the difference between the structure of the tested polymer and the molecular structure of AIE,and the blending doping concentration and the heating rate.2.During the preparation of the copolymerized polymer,it was been found that different RAFT reagent concentrations have an effect on the RAFT polymerization kinetics.This phenomenon was been studied by the applied magnetic field effect of free radical reaction.The main experimental method is to estimate the kinetic parameters by the action of a magnetic field.The experimental results show that the RAFT reagent concentration has a significant effect on the RAFT polymerization rate.When the concentration of RAFT reagent is low,the main factor affecting the RAFT polymerization rate delay is the cross-terminating rate constant.When the RAFT reagent is at a higher concentration,the concentration of intermediate free radical has a large effect on the cross-stop rate,causing the rate of polymerization to be constant as the concentration of the RAFT agent increases.Therefore,when performing RAFT polymerization,it is important to select a suitable concentration of RAFT reagent.