Nanocomposites of Highly Monodisperse Encapsulated Superparamagnetic Iron Oxide Nanocrystals Homogeneously Dispersed in a Poly(ethylene Oxide) Melt

Abstract

Nanocomposite materials based on highly stable encapsulated superparamagnetic iron oxide nanocrystals (SPIONs) were synthesized and characterized by scattering methods and transmission electron microscopy (TEM). The combination of advanced synthesis and encapsulation techniques using different diblock copolymers and the thiol-ene click reaction for cross-linking the polymeric shell results in uniform hybrid SPIONs homogeneously dispersed in a poly(ethylene oxide) matrix. Small-angle X-ray scattering and TEM investigations demonstrate the presence of mostly single particles and a negligible amount of dyads. Consequently, an efficient control over the encapsulation and synthetic conditions is of paramount importance to minimize the fraction of agglomerates and to obtain uniform hybrid nanomaterials.

Resonant Energy Transfer can Trigger Multiexciton Recombination in Dense Quantum Dot Ensembles

“…QDs/QRs were synthesized according to the protocol used earlier . The syntheses of the polymers are described elsewhere 2 summarizes the molecular weight characterization of the employed polymers.…”

Creating a synthetic platform for the encapsulation of nanocrystals with covalently bound polymer shells

“…We already introduced the thiol-ene click reaction with 1,6-hexanedithiol (HDT) to be a suitable method to crosslink and therefore stabilize the polymer shell in order to obtain homogeneously dispersed nanocrystals in a PEO matrix. 21 The thiol-ene clickreaction can be initiated with either a thermal radical initiator like 2,2′azobis(2-methylpropionitrile) (AIBN) or with a photoinitiator like 2,2-dimethoxy-2-phenyl-acetophenone (DMPA). Both initiation techniques are unsuitable for heat or UV sensitive materials.…”

Controlled Assembly of Block Copolymer Coated Nanoparticles in 2D Arrays

“…[2] ForABdiblock copolymers,nanoparticles can be selectively integrated into the AorBdomains,orinto the A/B interface. [11] However,t he self-assembly of block copolymer coated nanoparticles into ordered arrays has,tothebest of our knowledge,not yet been attempted or investigated.Herein we show that the direct self-assembly of block copolymer coated nanoparticles,asopposed to homopolymer [4] Later improved methods employed nanoparticles which were surface compatibilized with the targeted polymer domain.…”

“…As the conformational entropy of block copolymer chains is already reduced owing to their confinement at the domain interface,a dditional entropy losses owing to nanodomain incorporation immediately lead to problems of macrophase separation already at small volume fractions of nanoparticles. [11] However,t he self-assembly of block copolymer coated nanoparticles into ordered arrays has,tothebest of our knowledge,not yet been attempted or investigated. Coating the nanoparticles with al ayer of the corresponding matrix polymer not only minimizes enthalpic interactions,b ut also significantly reduces the loss of conformational entropy of the polymer chains.With this method, even full thermodynamic miscibility of nanoparticles and polymers can be realized, such that highest loadings with the formation of ordered nanoparticle arrays can be achieved.…”

“…[10] Theb est method to localize nanoparticles in block copolymer domains would thus be the direct coating of the nanoparticles with the respective block copolymers.T he attachment of block copolymers to nanoparticles has already been used for the fabrication of nanoparticles for biomedical applications. [11] However,t he self-assembly of block copolymer coated nanoparticles into ordered arrays has,tothebest of our knowledge,not yet been attempted or investigated.Herein we show that the direct self-assembly of block copolymer coated nanoparticles,asopposed to homopolymer…”