Study On Synthesis And Properties Of Fluorescent Silicone Elastomer Modified By Conjugated Biphenyl Ring

As a branch of organic silicon materials,fluorescent silicone materials have developed rapidly in recent years and have been widely used in fluorescent probes.fluorescent sensors,photon concentrators,fingerprint detection and other fields.Although the research on fluorescent materials has been relatively extensive,the research on organosilicon fluorescent materials generally takes a short time and the system is not yet perfect.For example,the currently studied doped fluorescent organic silicon materials are mainly doped with rare-earth fluorescent materials,while the related research on pure organic light-emitting molecules(without rare-earth metals)as fluorescent dopants is still relatively small.In addition,fluorescent silicone elastomers and fluorescent silicone materials with AIE/AIEE properties are rarely reported.Therefore,it is necessary to study new and efficient fluorescent additives used in silicone systems,especially in fluorescent silicone elastomers.Starting from the above background,this thesis has carried out the following research work:(1)By introducing a dimethylamino substituent at one end of the chalcone molecular skeleton,a high-efficiency fluorescent adjustable molecule with chalcone as the skeleton,which can be applied to the silicone system,was designed and synthesized.And it is added as a fluorescent doping material to the room temperature vulcanized silicone rubber synthesized by the hydrosilylation reaction to further synthesize a fluorescent silicone elastomer.At the same time,the influence of the doping amount on the fluorescence and mechanical properties of the elastomer was studied,and it was found that the elastomer can be given strong fluorescence performance with a very small amount of addition(Incorporated quality is one thousandth or even one ten thousandth).Moreover,the fluorescence emission wavelength can be adjusted by adjusting the addition amount,but when the material is doped in a large amount,the tensile strength of the elastomer will decrease.(2)Two kinds of biphenyl-modified fluorescent silicone molecules,IMBP and IPBP,were synthesized by the Heck reaction of 4-iodobiphenyl with double vinyl caps and vinyl silicone oil,respectively.Its structure was characterized by nuclear magnetic,infrared and other methods,and its fluorescence properties were further studied by ultraviolet absorption spectroscopy and fluorescence emission spectroscopy.Because of the same conjugate structure,the fluorescence properties of IMBP and IPBP are similar.The UV absorption peak in DMF solution is around 340nm,and the fluorescence emission peak is around 385nm and 405nm.The fluorescence emission wavelength of IMBP in the solid state has a larger red shift,and has a more obvious AIE/AIEE effect.For IPBP,with the increase of the grafting rate of the fluorophore,the fluorescence intensity of the material in the DMF solution at the same concentration gradually increases.(3)For the remaining vinyl groups in IPBP that can be used for cross-linking,two room temperature vulcanization cross-linking systems were designed using the hydrosilylation reaction and the mercapto-ene "click" reaction,respectively.And try to apply the synthetic fluorescent silicone elastomer to the synthesis of anti-counterfeiting signs.At the same time,the effects of different IPBP additions on the fluorescence properties,crosslinking density,mechanical properties,thermal properties and dynamic mechanical properties of two RTV silicone rubbers were studied.It was found that due to the introduction of IPBP,two new emission peaks were added around 430nm and 458nm,which gave the film fluorescence performance.As the amount of IPBP increases,the fluorescence emission intensity of the film gradually increases,the 5%thermal weight loss temperature and the 10%thermal weight loss temperature gradually decrease,the residual weight at 800? gradually increases,the thermal stability between 400? and 800? gradually increases,and the tensile strength,elongation at break,Shore hardness and Tan? value gradually increase.At the same time,after adding IPBP,a new peak appeared between-90? and-60?,indicating that the damping temperature range can be broadened by adding IPBP.