Study On The Synthesis And Properties Of Multistimulus Responsive Organic Silicon Fluorescent Materials

Organic silicon fluorescent materials combine the characteristics of both organic silicon materials and fluorescent materials and have attracted more and more researchers’ attention.Theoretically,it is an easy and direct method to prepare fluorescent functionalized organic polysiloxane materials by grafting small fluorescent molecules with conjugated structure as side or end groups to the polysiloxane main chain.In this way,many organic silicon fluorescent materials have been developed and successfully applied in explosive detection,fingerprint identification and other fields.However,compared with carbon-based small molecules or polymers with traditional fluorescent functions,organosilicon fluorescent materials are still relatively rare,and related reports mostly focus on synthesis methodology,with less attention paid to the interaction between siloxane main chain and fluorescent side groups and end groups.In fact,the introduction of the fluorescent side group/end group of the rigid conjugated structure will inevitably affect the properties of polysiloxane,and conversely,the properties of the fluorescent group will also change due to the restraining action of the polysiloxane chain segment.In-depth study of the interaction and synergy between the two will not only help us to understand the structure-property relationship of organic silicon fluorescent materials at a deeper level,but also hopefully bring new applications to materials and give them "versatility".Based on this consideration,this paper,taking the research of fluorescence group modified organic polysiloxane,through the Heck reaction in polysiloxane segment grafted on different fluorescent groups,the preparation of a series of fluorescent functional organic polysiloxane and silicone rubber elastomer,in-depth analysis of the interactions between fluorescent groups and siloxane chain segment,and make use of the synergy between them,The multistimulus response ability of the materials is further explored,which effectively expands the application field of organic silicon fluorescent materials.The main research content of this paper includes the following three aspects:Firstly,the preparation and fluorescence response performance of aniline-modified polysiloxane.Through Heck reaction,aniline-modified polysiloxane material(PN-1)was synthesized from terminal vinyl polydimethylsililoxane and 4-bromine-N,N-dimethylaniline.PN-1 has sensitive cyclic response to acidic environment in dispersed and aggregated state;PN-1 shows rapid solid-liquid transformation and fluorescence quenching.Secondly,preparation and fluorescence response of tetraphenyl modified polysiloxane.Through Heck reaction,vinyl terminated polydimethylsiloxane with different degree of polymerization,side-chain vinyl polymethylvinyl siloxane and 1-(4-bromophenyl)-1,2,2-triphenyl ethylene(TPE-Br)with aggregation induced luminescence effect(AIE)were used as raw materials respectively.A series of tetraphenyl modified fluorescent polysiloxane materials(PTPE1,PTPE2,PTPE3,PTPE-20%)were synthesized.The results show that PTPE series materials still show typical AIE effect.When the water content reaches 80%in THF/H2O mixed solvent,the fluorescence intensity increases sharply due to aggregation.However,due to the effect of polysiloxane chain segments on the movement of the fluorescence groups,the luminescence behavior of PTPE series materials is significantly different from that of TPE-Br.The maximum fluorescence emission wavelengthλem increases with the increase of the polymerization degree of the main chain,which can be redshifted from 455 nm to 495nm.Due to the synergistic effect of polysiloxane main chain and TPE side group,PTPE showed excellent thermal stimulation fluorescence response,with good circulability from room temperature to 190℃.Thirdly,preparation and fluorescence response of silicone rubber modified by tetraphenyl.The modified silicone rubber with two systems of dimethyl(RTPE0～RTPE4)and methyl phenyl(PRTPE0～PRTPE4)was prepared by using PTPE-20%containing residual vinyl as the fluorescent base adhesive and changing the number of its components.For RTPE,The tensile strength of RTPE1 was 4.42mpa,which was 125%higher than that of blank sample.The thermogravimetric temperature of modified silicone rubber is slightly lower than that of blank sample,and the residual weight is reduced.For PRTPE,The tensile strength of PRTPE3 was the highest,4.33mpa,which was 153%higher than that of the blank sample.The thermogravimetric temperature of modified silicone rubber is higher than that of blank sample,and its thermal stability is better.The modified silicone rubber showed a solvent-stimulated fluorescence response,and the fluorescence intensity of silicone rubber changed in different degrees under different solvents(THF/methanol).In addition,RTPE1 and RTPE2 also have a unique force-stimulated fluorescence response phenomenon,when the material is continuously stretched,the fluorescence intensity gradually increases.In the two systems of silicone rubbers,the movement mechanism between polysiloxane chain segment and AIE molecule is different in different environments,thus showing different luminescence behavior.