Studies On The Synthesis And Properties Of Polymer Matrix Sulfur Quantum Dots Nanocomposite

Quantum dots(QDs)are hailed as the next generation most promising luminescent material due to their excellent luminescent properties,and have been attracted a wide spread attention.Commonly like CdTe QDs,Graphene QDs,Carbon QDs,Perovskite QDs have been widely used in light-emitting devices(LED),sensitized fluorescent probe sensors,solar cells,biological cell imaging and other fields.Sulfur Quantum Dots(SQDs)is a new-reported kind of quantum dots.Except for the conventional fluorescence performance,SQDs also have some characteristics of sulfur elements,such as low toxicity,antibacterial activity,high reactivity and low cost,which show broad application prospects.Nonetheless,only two papers reported the synthesis of SQDs.There are many shortcomings like long heating time,high-cost,undistinguished performance which limit the further application of SQDs.So that,in this article we aim to break the bottleneck of disadvantages in SQDs synthesis process.After a series of studies,we report three different synthesis methods of SQDs,their characteristics are fast and efficient,low energy consumption and excited biocompatibility,respectively.Specific content as follows:(1)Using polysulfide ions as sulfur source,polyethylene glycol(PEG)as a stable dispersant,water as dispersion medium,and Oxygen as the oxidizing agent.Such reaction operated under pure oxygen atomsphere.The zero valence state sulfur emited from the polysulfide ions by oxidation and formed stability into nanometer sulfide quantum dots.It's worth noting that increasing the oxygen concentration can greatly increase the reaction rate,and the relative quantum yield was 6.2 %.An "Oxide-assisted Etching-Recrystallization" dynamic balance have been put forward to account for the transformations in reaction rate and size.The synthesized SQDs products can be dissolved in a variety of solvents,making them excellent machinability.(2)Using polysulfide ions as sulfur source,polyethylene glycol(PEG)as a stable dispersant,water as dispersion medium,and Oxygen as the oxidizing agent.We studied the oxidation of the polysulfide root liquid precursor at room temperature without heating,the SQDs also can be formed without heating,the advantages of such synthesis process are cost-effective and low requirements for the reaction equipment.In addition,the SQDs products showed characteristic detection ability for ferric ions and low biotoxicity(survival rate of cells >80% at 24 h and 0.5mg /mL concentration)and could be applied to live cell imaging.(3)Using polysulfide ions as sulfur source,hyperbranched polyglycerol(HPG)as a stable dispersant,we synthesized a new kind of SQDs with high light stability,smaller particle size,easy to modificaiton,low biological toxicity(survival rate of cells >82% at 24 h and 0.5mg /mL concentration),high biocompatibility.Besides,It has been used in cell imaging and animal imaging,and can be eliminated by metabolism within 24 h.