Polymer encapsulation of yttrium oxysulfide phosphorescent particles via miniemulsion polymerization

Abstract

Yttrium oxysulfide upconverting phosphor particles can absorb infrared light and emit dopant‐dependent visible phosphorescence. This unique optical property has been used for particle‐based immunoassay applications. In this study, upconverting phosphor particles were encapsulated with a functionalized polymer (carboxylated polystyrene) shell layer via several approaches, which included the following: (1) the physical adsorption of the carboxylated polystyrene polymer onto the phosphor surfaces, (2) the miniemulsification of the preformed carboxylated polystyrene in a solvent in the presence of the phosphor particles and the subsequent stripping off of the solvent, and (3) the miniemulsification and miniemulsion copolymerization of styrene and methacrylic acid in the presence of the phosphor particles with hexadecane as a costabilizer in combination with a surfactant (sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, or sodium dihexyl sulfosuccinate). Miniemulsion technology proved to be the most effective method for forming a functionalized polymeric nanoshell surrounding the phosphor particles. The morphology of the encapsulated phosphor particles was found to vary from symmetric core–shell (i.e., a uniform nanoshell layer with varying shell thicknesses), asymmetric core–shell, dumbbell‐like, or raspberry‐like partial encapsulation to multiparticle encapsulation. The amount of multiparticle encapsulation could be reduced by the postaddition of a surfactant, but it could not be eliminated completely. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1038–1054, 2007

Tailored composite polymer–metal nanoparticles by miniemulsion polymerization and thiol‐ene functionalization

“…Not only is this an unusually low population of empty nanoparticles for a composite miniemulsion system, but it compares favorably with the results from various other reported nanoparticle encapsulation methodologies, in which centrifugation procedures to remove empty particles are often a mandatory requirement 23, 43. Secondly, TEM imaging (Figure 3) showed no evidence of unencapsulated gold nanoparticles with all gold nanoparticles were strictly located in the interior of latex particles, such that these composite nanoparticles had a clearly visible shell of poly(divinylbenzene), approximately 10–20 nm in thickness surrounding a composite core.…”

“…As mentioned earlier, these two problems have been prevalent in many previous literature examples of composite nanoparticles formed by miniemulsion polymerization 30, 32, 37, 38, 41, 43…”

“…In order to facilitate the synthesis of composite nanoparticles using a minimized amount of gold nanoparticles (∼10 mg), the miniemulsion system was scaled down to a total volume of approximately 2 mL (cf. typical volumes of ∼100 mL30, 34, 43). It is noted, however, that through the course of this work miniemulsion synthesis was successfully carried out on various scales from 1–20 mL in total volume.…”

“…This simple method, which uses predominantly commercially available reagents, is appealing when compared with block copolymer self-assembly methods. Various literature reports describe the use of miniemulsion polymerization to prepare composite particles based on titania,29-31 calcium carbonate,32 magnetite,33-37 carbon black,38 alumina,39 silica,40, 41 zinc oxide42 and yttrium oxysulfide 43. However, in these cases the composite particles formed were subject to a variety of challenges: low inorganic content, inhomogeneous distribution of inorganic material, incomplete encapsulation of inorganic material, and large populations of pure (non-composite) polymer particles.…”

Encapsulation of Inorganic Nanoparticles by Miniemulsion Polymerization

“…However, when the organic phase was a mixture of styrene and n-butylacrylate, Al-Ghamdi et al [21] found that Solsperse 32000, a polyamine/polyester comb polymer with several anchor and several tails connected together in one molecule, was the best stabilizer for Ti0 2 . In the case of yttrium oxysulfide (Y 2 0 2 S) phosphorescent nanoparticles, the polymeric dispersant Solsperse 24000 improved Y 2 0 2 S dispersion and stability in styrene and methyl methacrylate monomers [22]. Fluorescent CdS/ZnS-coated CdSe or CdS quantum dots could be functionalized with a trialkylphosphine modified with an atom transfer radical polymerization (ATRP) initiator (i.e., 2-chloropropionate) [23], trioctylphosphine oxide (TOPO) [24,25], and 4-mercaptovinylbenzene [25] to be dispersed and stabilized in the organic phase previous to carry out the miniemulsion process.…”