[en] In this study, oligomeric phenylsilsesquioxane (OPSQ)-titania optical thin films were synthesized and characterized. OPSQ with the end group of Si-OR was prepared first. Then, it was reacted with titanium (IV) n-butoxide, followed by spin-coating and multi-step curing to form the optical thin films. Highly homogeneous and transparent films were obtained at the titania content of 0-54.8 wt.%. The titania domain in the prepared films was estimated to be 8 nm from the TEM diagram. The optical properties of the prepared hybrid films could be tuned by the titania content. By increasing the titania content from 0 to 54.8 wt.%, the absorption edge and refractive index of the prepared film were increased from 277 to 322 nm and 1.527 to 1.759, respectively. These results could be explained from the growing size effect of the titania domain. The optical loss of the studied planar waveguide by using the OPSQ-titania as the core layer decreased from 0.568 to 0.415 dB cm^-1 as increasing the titania content from 0 to 15.9 wt.%. It is resulted from the reduction of the C-H bonding density of the hybrid materials by increasing the titania composition. The prepared films could have potential applications for high refractive index coating or optical waveguides

[en] Novel ZrO₂/silicone hybrid materials useful for the encapsulation of light-emitting diodes (LEDs) are synthesized by in situ sol–gel reaction of zirconium propoxide directly in a commercial-grade silicone resin. The domain size of the produced ZrO₂ particles in the hybrid materials is controlled to be smaller than 350 nm based on SEM pictures to have a high optical transparency greater than 95% at 400 nm. The refractive index of the hybrid material increases from 1.52 to 1.62 when its ZrO₂ content is increased from 1 to 15 wt.%. In addition, these hybrid materials are stable enough to tolerate the treatment of soldering at 260 °C for 2 min. For the hybrid materials with the ZrO₂ content up to 7 wt.%, their weight-loss values are less than 0.25%. Finally, these hybrid materials are applied to encapsulate LEDs and their luminous flux is measured. The results showed that all the hybrid materials have higher luminous flux than the pristine silicone material. The luminous flux increased to a plateau value of 4.35 lm as the ZrO₂ content in the hybrid material was increased to 3.0 wt.%. For all the hybrid materials studied here, the ZrO₂/AB3 hybrid is considered to be the most suitable candidate as the encapsulating material for the LED used in this study. - Highlights: • Highly stable ZrO₂ particles were synthesized in a commercial-grade silicone material. • The transmittance of the ZrO₂/silicone hybrid is higher than 95% at wavelength of 400 nm. • The luminous flux of LEDs was greatly enhanced as encapsulated with the ZrO₂/silicone hybrids

[en] In this paper, the morphology and photophysical properties of non-woven and aligned ES nanofibers prepared from the ternary blends of poly(9,9-dioctylfluorenyl-2,7-diyl) (PFO) / poly(2,3-dibutoxy-1,4-phenylene vinylene) (DB-PPV) / poly(methyl methacrylate) (PMMA) using a single-capillary spinneret are reported. Various PFO and DB-PPV phase-separated structures in the ES nanofibers were found by two different solvents: ellipsoidal DB-PPV (10-40 nm) and fiber-like PFO (20-40 nm) in the PMMA using chloroform, while fiber-like DB-PPV (10-20 nm) and fiber-like PFO (20-30 nm) using chlorobenzene. Such different PFO and DB-PPV structures resulted in various energy transfer/emission colors in the ES nanofibers. Moreover, highly aligned luminescence PFO/DB-PPV/PMMA blend ES nanofibers prepared from chlorobenzene showed a much higher polarized emission than the non-woven and the emission colors changed from blue to greenish-blue to green as the DB-PPV composition increased. The different polarized emission characteristics between PFO and DB-PPV in the ES nanofibers also led to varied emission colors at different angles. The present study suggests the morphologies and emission characteristics of the multicomponent ES nanofibers could be efficiently tuned through solvent types and blend ratios of semiconducting polymers.

[en] We synthesized AuPt alloyed nanoparticles in colloidal solution by a one-pot procedure based on synchrotron x-ray irradiation in the presence of PEG (polyethylene glycol). The exclusive presence of alloyed nanoparticles with fcc structure was confirmed by several different experiments including UV-vis spectroscopy, x-ray diffraction (XRD) and transmission electron microscopy (TEM). The composition of the AuPt alloyed nanoparticles can be varied in a continuous fashion by simply varying the feed ratios of Au and Pt precursors. The nanoparticles exhibited colloidal stability and biocompatibility, important for potential applications.