Preparation And Application Of Stimuli-Responsive Magnetic Nanocomposites Based On Aggregation-induced Emission

The luminous color and intensity of the stimulus-responsive luminescent material can be adjusted by external stimuli(solvent,heat,mechanical,chemical,etc.).By designing and combining materials with different stimulus-responsive behaviors,the application of responsive luminescent materials in different occasions and different fields can be satisfied and expanded.However,traditional stimulus-responsive luminescent materials have the phenomenon of"Aggregation-Caused Quenching"(ACQ),they can only emit light well in dilute solutions;once the concentration increases or becomes aggregated,the fluorescence will be quenched,which greatly limits the scope of application of fluorescent materials.The aggregation-induced emission(AIE)materials developed in recent years overcome the shortcomings of traditional luminescent materials ACQ and promote the application of luminescent materials in high concentrations.For magnetically responsive materials,its potential application value in magnetic resonance imaging,medical diagnosis,storage devices,catalysts and sensors has become a research hotspot.However,the combination of fluorophores and magnetic nanoparticles(MNPs)is a challenging problem.This is because direct contact between the fluorophore and MNPs may cause energy or electron transfer,leading to fluorescence quenching.Although many excellent magnetic materials have been created,their ability to be used as colored materials and optical materials is limited due to their deep colors and broad band absorption characteristics.Therefore,it is necessary to develop nanocomposite materials that integrate fluorescence,multiple stimulus responsiveness and magnetism.In this article,we combine AIE groups,responsive polymers and superparamagnetic materials to design nanocomposites and gels with fluorescent properties,stimulus responsiveness,and superparamagnetic properties in order to realize real-time visualization of changes in the external environment monitor,and the potential applications of the prepared stimulus-responsive magnetic composite materials were explored.The specific research content is as follows:(1)A multifunctional Fe₃O₄@a Si O₂@P(DMAEMA-co-TPEE)yolk-shell structure AIE fluorescent probe(YS-NPs)was prepared by sol-gel deposition and SI-RAFT polymerization.Experimental results show that YS-NPs can be used as fluorescent probes to visually monitor changes in p H,CO₂,temperature,and magnetic fields.What's more,YS-NPs solutions exhibit high colloidal stability during environmental changes.(2)The P(PEGA)-b-P(AA-co-TPEE)diblock copolymer with AIE characteristics was synthesized by RAFT polymerization.Utilizing the coordination of the polymer carboxyl group and holmium ion to change the hydrophilic-hydrophobic ratio of the chain segment can form superparamagnetic colorless assemblies with different morphologies.The relationship between the fluorescence intensity and the concentration of holmium ion,the magnetization of the assembly and the morphology of the assembly was established.Coordination of P(PEGA)-b-P(AA-co-TPEE)and holmium ions was used to assemble the coated dye,and the study on dye loading and release was carried out,which confirmed the potential application of the assembly in the field of drug loading.(3)The superparamagnetic Fe₃O₄ colloidal nanoclusters were synthesized by hydrothermal method,and the relationship between the amount of EDTA-2Na and Na Ac and the size of the crystal clusters was studied.Then the classic St(?)ber process was used to synthesize Fe₃O₄@Si O₂ core-shell nanostructures.The relationship between the concentration of TEOS and the thickness of the shell was studied.The prepared Fe₃O₄@Si O₂ was used as a filler in PAM-PDMAEMA-PTPEE hydrogel to obtain a structural color hydrogel with AIE properties.The influence of temperature changes on the structural color and fluorescence intensity of the hydrogel was studied.The results show that the hydrogel can achieve dual responses to the gel structure color and fluorescence intensity at different temperatures.