The Taguchi method, a statistical design with an L8 orthogonal array, was adopted to optimize the synthetic conditions of mesoporous silica nanoparticles (MSNs) with respect to particle size and structural properties. The amount of the silica source (i.e., tetraethoxysilane), pH value, and reaction time were selected as significant parameters affecting the size and structural properties of the synthesized MSNs. Particle sizes ranging from 17 to 247 nm were successfully controlled by the Taguchi method, and the statistical data based on experimental results indicated that the pH value of the silica/surfactant precursor solution had a greater influence (57%) on particle size than did reaction time and the TEOS amount (29% and 13%, respectively). The effects of individual parameters on particle size and structural properties, such as surface area and structural ordering, were also investigated by changing one parameter at a time. We concluded that the pH value strongly affected mesostructural ordering and particle size. Longer reaction times in basic conditions had little effect on structural ordering but caused erosion of the MSN silica framework, resulting in smaller particle sizes. The minimum amount of TEOS for ordered MSNs was 5 mL, and more TEOS slightly increased the particle size of the synthesized MSNs. The rational design and systematic investigation of synthetic conditions for MSNs with controllable particle sizes and structural properties presented in this study show great potential for MSN-based catalytic and biomedical applications.

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We report the study of the fluorescence switching properties of the conjugated copolymers containing triphenylamine, fluorene, benzo[2,1,3]thiadiazole, and cyclic urea moieties. The copolymers show excellent thermal stability and good solubility in polar organic solvents. While the electrofluorescent device (EFD) of P1 emits yellow light under UV excitation, fluorescence intensity is switched off upon electrochemical oxidation. In addition, the fluorescent behavior of the EFD of P1 can be reversibly switched between the non-fluorescent (oxidized) state and the fluorescent (neutral) state with a superb contrast ratio (I f /I f0 ) of 21.4. Furthermore, a white-light electrochemical fluorescence switching device is achieved by blending of P1 (yellow) with P2 (blue). Since the fluorescent conjugated polymers of P1 and P2 have their emission simultaneously quenched under the low working potential, the EFD could show a white-dark state of fluorescence with a high contrast ratio (I f /I f0 ) of 14.6.

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This study illustrates the directed self-assembly of mesoporous TiO2 with magnetic properties due to its colloidal crystal structure with Fe3O4. The Fe3O4 nanoparticles were synthesized using co-precipitation techniques to a size of 28.2 nm and a magnetic saturation of 66.9 emu g(-1). Meanwhile, mesoporous titania nanoparticles (MTNs) with a particle diameter of 373 nm, a specific surface area of 236.3 m(2) g(-1), and a pore size of 2.8 nm were prepared by controlling the rate of hydrolysis. Magnetic colloidal crystals (a diameter of 10.2 μm) were formed by the aggregation of Fe3O4 and MTNs caused by the interface phenomena during solvent evaporation in emulsion. Even the anatase octahedrite produced from the colloidal crystal after a hydrothermal reaction retained a magnetic saturation of 2.8 emu g(-1). This study also investigates the photodegradation activity of our synthesized material as a photocatalyst, while utilizing its capability for magnetic separation to prove its usefulness in catalyst recycling.

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