Construction And Properties Of Inorganic-Organic Nanohybrid Systems Based On Fluorescent Quantum Dots

Fluorescent quantum dots show wide application prospects in the fields of light-emitting devices,biomedicine,and sensing based on their excellent optical properties.However,their inherent instability,weak processability,and poor functional diversity limit their further application.Inorganic-organic hybrid materials based on polymers and fluorescent quantum dots can not only enhance the dispersion and stability of quantum dots but also achieve the functional integration and performance improvement of hybrid materials.But most synthetic methods of inorganic-organic hybrid materials are tedious and it is difficult to achieve precise construction hybrid nano-assembly.For these questions,this paper focuses on the development of new synthesis strategies with enhanced performance of hybrid materials and exploring the mechanism of functional ligands for the control of hybrid assembly structures.The main research contents are as follows:1.A binary fluorescent emitting T-PNI@QDs nanohybrid assembly structure was constructed by the coordination-induced assembly.Red-emitting Cd Te/Zn S quantum dots and blue-emitting aggregation-induced emission（AIE）polymer micelles with coordination functions were utilized as building blocks.The construction of T-PNI@QDs was based on the coordination interaction between the sulfhydryl groups on the micelles′surface and the quantum dots.The blue-emitting aggregation-induced emission（AIE）polymer micelle was obtained by self-assembly double-terminal functional poly（isopropyl acrylamide）（T-PNI-SH）with thiol and tetraphenylethylene（TPE）groups in water.The nano-assembly can realize the specific detection of the explosive picric acid（PA）in an aqueous solution and the detection limit can reach 4.0μM.The self-assembled structure can be effectively regulated from worm-like micelles to core-shell nanostructures by adjusting the ratio between quantum dots and polymers during the assembly process.This work clarified the mechanism of quantum dots in the hybrid assembly process and provided a simple and efficient method for the design of multicolor fluorescent materials.2.Organic-inorganic hybrid perovskite materials PQDs@SiO₂-d was fabricated by the strategy of functional ligand-assisted hybrid assembly,which can be used directly as a cellular labeling agent for cell imaging.By in-situ co-hydrolysis and condensation regulation of（3-aminopropyl）triethoxysilane（APTES）,superhydrophobic perfluorooctyltrimethoxysilane（PFMS）,and hydrophilic siloxane terminated polyethylene glycol（Si-PEG）,the resulted PQDs@SiO₂-d can retain a high fluorescence quantum efficiency（93%）and maintain great polar solvents dispersibility,stability,and excellent anti-ion exchange capacity in this strategy.In this ligand-assisted re-precipitation reaction process,APTES,PFMS,and polymer ligand Si-PEG can construct the SiO₂ shell through co-hydrolysis,APTES and protonated APTES（APTES⁺）are used as alternatives to oleic acid/oleylamine（OA/OAm）ligands,PFMS imparts excellent resistance to harsh environments,and hydrophilic Si-PEG improves the dispersibility and biocompatibility of the resulting material.The polar solvent stability,dispersibility,and biocompatibility of highly fluorescent inorganic-organic hybrid perovskite materials have been improved through the ingenious association of various functional ligands.In addition,the role and mechanism of ligands in the material formation process in this strategy are clarified,which is of great significance for the ligand engineering of perovskite materials and the directional design and functional regulation of complex structures.3.Highly hydrophobic F-PQDs/PFOEMA inorganic-organic hybrid perovskite nanospheres were successfully constructed through an in situ self-assembly strategy by combined ligand exchange post-modification method and photo-induced reversible addition-fragmentation chain transfer（PET-RAFT）polymerization.The hybrid nanospheres exhibit excellent environmental stability and can be used as phosphors to construct white light-emitting diodes（WLEDs）.In this method,perfluorooctanoic acid（PFOA）was modified to the surface of Cs Pb Br₃,avoiding their further degradation during photo-polymerization.Furthermore,the dipole-dipole interaction between the perfluoroalkyl chain of PFOA decorated on the surface of perovskite quantum dots（F-PQDs）and the fluorocarbon chain of2-（perfluorooctyl）ethyl methacrylate（FOEMA）monomer drives the enrichment of polymerized monomers on the perovskite surface,improving the encapsulation efficiency between PQDs and polymer microspheres.In this strategy,fluorescent quantum dots exhibit multiple functions in the construction of hybrid materials,PQDs not only serve as the"luminescent center"of hybrid microspheres but also as the"catalytic center"of the polymerization.Also,some concepts of traditional suspension polymerization and precipitation polymerization have been expanded and extended.4.Polymerization-induced self-assembly（PISA）technology was utilized in the construction of perovskite-based organic-inorganic hybrid nanomaterials with stable fluorescence emission on the basis of the previous chapter.This method is used F-PQDs to serve as both photocatalyst（PC）and fluorescence center of the hybrid materials,poly（poly（ethylene glycol）monomethyl ether methacrylate）（POEGMA）as the macromolecular chain transfer agent（macro-CTA）and FOEMA as the monomer,which combined the perovskite-catalyzed PET-RAFT polymerization and photo-regulated PISA（Photo-PISA）technique for the first time.Regulation of the ratio between the POEGMA block and the PFOEMA block achieves the morphology transition from nanorods to spindle-like nano assemblies during the PISA process.In this process,the presence of POEGMA solvophilic blocks effectively enhanced the polymerization conversion of FOEMA;meanwhile,the spontaneous aggregation of solvophobic PFOEMA achieved the appearance of liquid crystal phase（LC）in nano assemblies.Based on PQDs catalyzed PET-RAFT polymerization,the combination of Photo-PISA technology avoids the cumbersome steps of conventional PQD/polymer nano-hybrid material construction and also provides a new perspective for the synthesis of organic-inorganic nano-hybrid materials through PISA technology.