Research On Assembly,Performance And Application Of Composites Based On Carbon Dots

Carbon dots?CDs?have attracted extensive attention from researchers due to their outstanding properties of fluorescence,biocompatibility,and non-toxicity.However,most researches have focused on its fluorescence properties and applications,studies concerned about its phosphorescence and ultraviolet absorption properties still lacked.In view of the problems including high price,toxicity,and easy quenching of phosphorescent materials as well as poor stability,narrow absorption range,and poor compatibility of traditional ultraviolet absorbers,this paper has conducted research on the following three aspects:1)The silane functionalized carbon dots?Si Ds?were synthesized in one step by hydrothermal method,then they were combined with Sr SO₄ by electrostatic assembly.Si Ds@Sr SO₄had long phosphorescence lifetime?1.04 s?,high phosphorescence quantum efficiency?8.34%?,excellent thermal stability,light stability and wide p H adaptability.Further analysis of their phosphorescence sources through comparative experiments confirmed that the C=O bond in the urea group on the surface of Si Ds and the heavy atom effect of Sr SO₄had important effects on the phosphorescence intensity and lifetime of CDs@Sr SO₄.This material exhibited excellent effects in information encryption and anti-counterfeiting.2)The application of carbon dots in anti-aging PE film was studied.Carbon dots and Ba SO₄ were compounded through electrostatic assembly.The compound CDs@Ba SO₄ had the common characteristics of CDs and Ba SO₄:high fluorescence,high ultraviolet absorption characteristics and good stability.CDs@Ba SO₄ was used as an additive for PE masterbatch to prepare a film and the film exhibited excellent high ultraviolet absorption characteristics with significantly improved anti-aging performance.Meanwhile,due to the nano-toughening effect of CDs@Ba SO₄,the film elongation at break increased and could convert ultraviolet light into blue light which was of great significance to plant growth.These remarkable characteristics indicates that the film will have huge application prospects in the field of agricultural greenhouses.3)The application of carbon dots in the anti-aging of waterborne coatings was explored.EDA-CDs with excellent UV absorption properties and cheap price of raw material amongst four different types of carbon dots were selected.This water-soluble carbon dot had good compatibility with water-soluble acrylic resin emulsion and could achieve full UV absorption effect with thermal and light stability.SEM after accelerated aging experiments showed that anti-aging properties of acrylic coatings with EDA-CDs were significantly improved.