Stable and highly efficient light-emitting functional silicone materials have shown broad application prospects in the fields of thin film sensors.At present,the simplest way to construct fluorescent silicone materials is to physically doped fluorescent molecules into the silicone matrix.But the inhomogeneity and instability caused by the physical encapsulation of fluorescent molecules in the matrix seriously reduce the service life of the device.From the above background,this thesis proposes a new strategy for the macromolecularization of fluorescent substances,and by incorporating fluorescent polymers into silicone substrates a functional silicone material that is migration resistant and highly efficient in solid state luminescence is prepared.Two types of fluorescent polymers,the aggregation-induced quenching(ACQ)fluorescence unit-carbazole unit and the aggregation-induced emission(AIE)fluorescence unit-tetraphenylethylene unit,were prepared and the fluorescence properties,migration resistance and stimulus response of silicone films prepared by adding these two types of fluorescent polymers were investigated.The specific work is divided into two parts as follows:(1)A fluorescent polymer with a carbazole unit as a side group was synthesized by Reversible Addition-Fracture Chain Transfer(RAFT)polymerization using a vinyl carbazole monomer with ACQ properties.FT-IR,NMR and GPC confirmed the successful synthesis of polyvinyl carbazole(PVK)with molecular weights in the range of 2000-20,000 g/mol.The results of the fluorescence spectrophotometer showed that PVK exhibited aggregation-induced quenching(ACQ)properties,and the higher molecular weight PVK showed better fluorescence properties,therefore the study focused on PVK with a molecular weight of 20,000 g/mol as an example.A macromolecular additive fluorescent silicone film was prepared by doping this ACQ polymer into a silicone substrate.The fluorescence properties were studied by UV-Vis spectrophotometer and fluorescent spectrophotometer.It was found that the fluorescence emission of the films started to be quenched when the addition of polyvinyl carbazole exceeded 0.4 wt%.This phenomenon can be explained by the SEM test results,where the size of the polyvinyl carbazole aggregates in the films increased from 200 nm to 1 μm when the addition of polyvinyl carbazole was increased from 0.1 wt% to 0.7wt%,prompting an aggregation-induced quenching of the fluorescence in the films.The migration resistance and fluorescence responsiveness of the films were investigated in combination with fluorescence spectroscopy and it was found that the films maintained about 80% of their fluorescence emission in solvents such as n-hexane,ethanol and cyclohexane,which do not dissolve polyvinyl carbazole,showing good migration resistance.However,in the good solvents of polyvinyl carbazole such as tetrahydrofuran and toluene,the fluorescence emission properties of the films are only maintained by 40%.When stretched to 150%,the fluorescence emission of the film appears enhanced for about 15%,showing a certain stimulus responsiveness to strain.(2)The fluorescent unit of tetraphenylethylene(TPE)with AIE properties was chosen to introduce polymerizable double bonds into the TPE through the ester-forming reaction of hydroxyl groups with acryloyl chloride,and finally a fluorescent polymer with a TPE unit in the side chain was obtained by RAFT polymerization.The successful synthesis of tetraphenyl ethylene acrylate polymer(TPE-P)with molecular weights ranging from 4000-6000 g/mol was determined by FT-IR,NMR and GPC tests.The yield of 6000 g/mol TPE-P is only about 30% due to the steric hindrance effect of TPE,so the study focuses on 4000 g/mol TPE-P with a yield of 80%.Fluorescence spectra show that TPE-P has aggregation-induced emission(AIE)properties.By adding this AIE polymer to the silicone matrix,TPE-P/fluorescent silicone films were obtained.The fluorescence spectra showed that the fluorescence emission intensity of the TPE-P/silicon film was more than 20 times higher than that of the TPE-M/organosilicon film of the same mass concentration,and the fluorescence efficiency reached 30.43%,marking the highly efficient solid-state fluorescence of the TPE-P/organosilicon film.This phenomenon is discussed in relation to confocal laser scanning microscopy tests,which show that TPE-M is well dispersed in the silicone matrix due to covalent bonding,while TPE-P forms a large number of luminescent aggregates in the matrix.In combination with UV absorption spectroscopy,the migration resistance of the TPE-P/silicone films was characterized.It was found that the films maintained an absorbance of about 90% in solvents such as hexane,ethanol and cyclohexane,which do not dissolve TPE-P.Even in leaching experiments with good solvents for TPE-P such as tetrahydrofuran and toluene,the films maintained an absorbance of more than 70%,reflecting the good migration resistance of the films.Finally,the fluorescence responsiveness of the TPE-P/organosilicon films is explored.The fluorescence emission of the films was found to be almost completely quenched at 170 °C.Organic solvents such as toluene and tetrahydrofuran,which can swell silicone substrates and dissolve TPE-P,also cause fluorescence quenching in the film.A stretching strain of 150% leads to a reduction in fluorescence emission of approximately35% in the film.After verification in cyclic experiments,we determined that the films have a stable and reversible fluorescence response to strain,temperature and some organic solvents. |