The Preparation Of Upconversion Nanomaterials And Surface Modification Using Light-Driven ATRP

Since upconversion nanoparticles(UCNP)were discovered,they have been widely used in biomarkers,bioimaging,drug delivery,3D displays and solar cells due to their high chemical stability and good biocompatibility.However,the upconversion nanoparticles tend to agglomerate as for the surface energy is high.This property greatly limits their applications,so the surface modification of upconversion nanoparticles is necessary.For a large number of nanomaterials,surface initiated Atom transfer radical polymerization(ATRP)is a very important and effective surface modification strategy.Compared with the traditional ATRP,the light-driven ATRP does not require metal catalysts and expensive organic ligands,and can be mediated only by ultraviolet light to achieve the polymerization of monomers.Therefore,this method is more simplicity,economical and environmentally friendly.In addition,some properties of UCNP are closely related to their size and morphology.The size and morphology of UCNP can be adjusted by using different ligands.Therefore,different ligands were used to prepare UCNP with different morphologies by solvothermal method,and then the UCNP modified with polymethyl methacrylate(PMMA)were prepared by light-driven ATRP method.A series of characterizations of the resulting UCNP were performed.The details are as follows:1.Upconversion nanoparticles with diameters of about 50 nm and simple multiarmed morphologies were prepared by solvothermal method assisted with ligand 10-hydroxydecanoic acid,and then the upconversion nanoparticles modified with PMMA were prepared by light-driven ATRP method using MMA as monomers.2.Upconversion nanoparticles with diameters of about 200 nm and non-smooth rodlike morphologies were prepared by solvothermal method assisted with ligands 10-hydroxydecanoic acid and oleic acid,and then the upconversion nanoparticles modified with PMMA were prepared by light-driven ATRP method using MMA as monomers.3.The hydroxyl group of 10-hydroxydecanoic acid was modified by the esterification between the hydroxyl group and 2-bromoisobutyryl bromide to prepare bi-functional ligand as the light-driven ATRP initiator.Then,the upconversion nanoparticles with light-driven ATRP initiation sites were prepared by solvothermal method using this bi-functional ligand.The diameters of prepared upconversion nanoparticles were about 100 nm and the morphologies were approximately spherical.Then the upconversion nanoparticles modified with PMMA were prepared by light-driven ATRP method using MMA as monomers.4.The upconversion nanoparticles modified with PMMA were added to the MMA monomer solution with AIBN initiator,and dispersed by ultrasonic.Transparent and upconversion photoluminescent PMMA nanocomposites were prepared by in-situ polymerization.The prepared transparent upconversion nanocomposites were characterized,and the effect of nanoparticles content on the properties of the nanocomposites was studied.