| In recent years,the rapid development of nanoscience and technology has promoted the rapid progress of chemistry,physics,biology,medicine and many other subjects.Among them,nanomaterials have attracted great interest due to their excellent properties in optics and electricity.Quantum dots(QDs),as an important branch of semiconductor fluorescence nanomaterials,have unique properties in size,composition,shape and surface state,which has great application potentials in the fields of bioimaging,detection and photoelectron.?-?-? Quantum dots are a member of the quantum dots family,composed of less toxic elements(not containing Cd,Hg)and their ofluorescence emission wavelength of the ?-?-? Quantum dots can be adjusted from the ptical band gap is wide.The visible region to the near-infrared region so that they have superiority on biological living body imaging and can replace the chromium series quantum dots.AgInS2 QDs are a kind of ?-?-? Quantum dots,and due to the high reactive activity of Ag+,AgInS2 QDs with different particle radius,structures and fluorescence emission wavelength can be synthesized by changing the ratio of the precursors,reaction temperature and reaction time.However,most of the synthesis methods are based on batch reactors,leading to uneven distribution of temperature and concentration,bringing poor homogeneity to the nanomaterials and low reproducibility between batches.The controllable synthesis of high performance AgInS2 QDs still remains to be challenging.Droplet microreactors are outstanding in this situation,because not only there is shorter intermolecular diffusion distance,more effective mixture of reagents,faster mass/heat transfer and better control of reaction conditions in droplet microreactors,but also they can be integrated with specific functional units to realize the control and in-situ monitoring of quantum dots synthesis,thus used in QDs preparation and property control.In this work,the droplet microreactors were used for controllable continuous synthesis and ripening of water-soluble AgInS2 QDs.The primary contents has been summarized as follow:(1)The temperature-controllable droplet microreactors were utilized to continuously synthesize water-soluble AgInS2 QDs,and the temperature influence on the fluorescence properties of AgInS2 QDs was also studied.Two dispersed phases(one was a mixed solution of Ag/In precursors,the other was a solution of Na2S precursor)presented a stable laminar flow before arriving at the flow-focusing structure.After that,water-in-oil(W/O)droplets were formed by the shear of the continuous phase(fluorinated oil).AgInS2 QDs with MPA as surface ligands were rapidly and continuously synthesized in these microreacotors with good stability and reproducibility.By changing the temperature of the reaction region,the AgInS2 quantum dots with different particle radius and adjustable fluorescence wavelength(590-720 nm)were prepared,and the effects of temperature on the fluorescence properties were also investigated based on that.(2)"Synthetic-ripening" integration droplet microfluidic chips were utilized to realize continuous synthesis and ripening of water-soluble AgInS2 quantum dots,with improved fluorescence quantum yield.After the synthesis process,the droplet flowed into the ripening area downstream of the chip to realize quantum dot maturation.We investigated the effects of different ripening temperatures on the emission wavelength,particle size and crystal structure of AgInS2 quantum dots.Products with the maximum quantum yield of 10.3%can be obtained at suitable synthesis and ripening temperatures.This method makes the synthesis and ripening of quantum dots into an online continuous process.Compared with the conventional reactors,the reaction time was greatly shortened and the synthesis efficiency was effectively improved. |
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