This study investigated the nanoemulsion technique as a means to synthesize carbonated hydroxyapatite (CHAp) nanospheres which could be used to produce composite tissue engineering scaffolds. CHAp nanospheres were successfully synthesized by mixing an acetone solution of Ca(NO(3))(2).4H(2)O with an aqueous solution of (NH(4))(2)HPO(4) and NH(4)HCO(3). Four reaction temperatures, namely, 4, 25, 37 and 55 degrees C, were investigated and no surfactant was added in all nanoemulsion processes. Wet slurries of CHAp from the nanoemulsions were freeze-dried to obtain dry powders. X-ray diffraction (XRD) results showed that the as-synthesized CHAp nanoparticles were mainly in an amorphous state. After calcination at 900 degrees C, the apatite became well crystallized. Fourier transform infrared (FTIR) spectroscopy showed that the CHAp was B-type substitution. Both scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that the CHAp particles were spherical in shape and that their sizes were in the nanometer range. The successful synthesis of CHAp nanospheres is a critical step forward in our efforts to fabricate bone tissue engineering scaffolds using the selective laser sintering technology.

Flexible organic light-emitting diode (OLED) devices based on polymer substrates have attracted worldwide attention. However, the current OLED polymer substrates are limited due to weak thermal stability, which is not compatible with the high temperature in OLED fabrication. Here, we developed a novel nanocellulose/polyarylate (PAR) hybrid polymer substrate with both high transparency and excellent thermal properties. Benefiting from the nanometer scale of the cellulose nanofibrils (CNFs) and the efficient interfacial interaction with PAR, the substrate exhibited greatly improved thermal stability, with a glass transition temperature of 192 °C, the thermal decomposition temperature of 501 °C, and upper operating temperature up to over 220 °C. Meanwhile, the hybrid substrate exhibits outstanding mechanical properties. Notably, no apparent transparency loss was observed after the CNF addition, and the hybrid substrate maintains a high transmittance of 85% and a low haze of 1.75%@600 nm. Moreover, OLED devices fabricated on the hybrid substrates exhibit a much improved optoelectrical performance than that of the devices fabricated on the conventional poly(ethylene terephthalate) (PET) substrates. We anticipate this research will open up a new route for fabricating flexible high-performance OLEDs.

Flexible organic light‐emitting diode (OLED) displays have attracted worldwide attention and colorless polyimides (CPIs) are their key substrate materials. However, desirable CPIs are difficult to obtain since the thermal and mechanical properties are sacrificed during CPI production through modification of colored polyimide. Here, a cellulose nanocrystal (CNC)/CPI hybrid substrate with high optical, mechanical, and thermal properties is introduced. Due to the outstanding mechanical and thermal properties of CNCs as well as their strong interfacial interaction with CPI matrix, the sacrificed properties are made up and hybrid substrate is demonstrated strikingly improved thermal properties and mechanical properties with thermal decomposition temperature of 555 °C, upper operating temperature of 320 °C, glass transition temperature of 289 °C, coefficient of thermal expansion of 31.62 ppm K−1, tensile strength of 128 MPa, elastic modulus of 3.72 GPa, and folding capacity of 160 000 times. Particularly, the substrate keeps an excellent transmittance of 86% at 600 nm and it is colorless. The OLED devices built on the hybrid substrates show outstanding performance, which is superior to that of OLED@CPI, and comparable to that of OLED@glass. It is expected that this work will open new avenues for fabricating high‐performance and low‐cost flexible OLED devices.

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