3D Printable Hybrid Gel Made of Polymer Surface-Modified Cellulose Nanofibrils Prepared by Surface-Initiated Controlled Radical Polymerization (SI-SET-LRP) and Upconversion Luminescent Nanoparticles.

A cellulose nanofibril-based hybrid gel material was developed by grafting the polymerized stearyl acrylate (PSA) and upconversion nanoparticles (UCNPs) onto cellulose nanofibrils (CNFs) via Cu-mediated radical polymerization (SET-LRP) to create a highly cross-linked CNF system. A two-step strategy was exploited to surface-exchange the ligand of the UCNPs from a hydrophobic ligand (oleic acid) to a hydrophilic small-molecule ligand (2-acrylamido-2-methyl-1-propanesulfonic acid, AMPS) and therefore be suitable for SET-LRP. The characteristics and properties of the hybrid material (UCNP-PSA-CNF) were monitored by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), rheology, X-ray diffraction (XRD), and microscopic analysis.

Bulk-like emission in the visible spectrum of colloidal LiYF:Pr nanocrystals downsized to 10 nm.

Though Pr doped LiYF (LiYF:Pr) bulk crystals are a well-known laser gain material with several radiative transitions, their nanocrystal counterparts have not been investigated with regards to these. Through downsizing to the nanoscale, novel applications are expected, especially in composite photonic devices. For example, nanocrystals in stable colloidal form with narrow size distribution are highly desirable to reduce scattering in such composites.

Simple one pot synthesis of luminescent europium doped yttrium oxide YO:Eu nanodiscs for phosphor converted warm white LEDs.

Yttrium oxide (YO) is considered as one of the best host lattices for europium (Eu) based red emitting phosphors because of its unit cell and good photo-saturation properties. As a bulk material, it reaches nearly 100% quantum yield. However, providing high quality nanosized materials for the LED industry is still a challenge and not easily accomplished.

Effect of the crystal structure of small precursor particles on the growth of β-NaREF4 (RE = Sm, Eu, Gd, Tb) nanocrystals.

The origin of the narrow particle size distributions obtained in the oleic acid-based synthesis of hexagonal phase β-NaREF(4) nanocrystals (RE = Sm, Eu, Gd, Tb) has been investigated. Compared to the standard synthesis, the growth conditions were simplified by using small purified particles of either α-NaREF(4) (cubic phase) or β-NaREF(4) (hexagonal phase) as single-source precursors, thereby avoiding the complications arising from the simultaneous presence of molecular educts and intermediately formed small particles. The study shows that α-phase as well as β-phase particles grow by Ostwald-ripening but narrow particle size distributions of the β-NaREF(4) product particles are only obtained when α-phase precursor particles are employed.

An electron paramagnetic resonance spectroscopic investigation on the growth mechanism of NaYF4:Gd nanocrystals.

Doped nanocrystals of NaYF(4) and NaGdF(4) are currently studied as upconversion luminescence markers and magnetic resonance imaging contrast agents. An EPR investigation on the growth mechanism of NaYF(4):Gd and NaGdF(4) nanocrystals showed that these nanomaterials grow in the standard oleic acid-based reaction medium by a dissolution/recrystallization mechanism and not by the aggregation or oriented attachment of smaller particles.

Surface modification of luminescent lanthanide phosphate nanorods with cationic "Quat-primer" polymers.

"Quat-primer" polymers bearing cationic groups were investigated as a surface modifier for Tb-doped cerium phosphate green-emitting fluorescent nanorods (NRs). The NRs were synthesized by a microwave process without using any complex agents or ligands and were characterized with different analytical tools such as X-ray diffraction, transmission electron microscopy, and fluorescence spectroscopy. Poly(ethyleneimine) partially quarternized with glycidyltrimethylammonium chloride was synthesized separately and characterized in detail.