Xuehui Liu

Facile Approach to Large-Scale Synthesis of 1D Calcium and Titanium Precipitate (CTP) with High Electrorheological Activity

Nanorods of calcium and titanium precipitate (CTP) were prepared via a simple precipitation route in an ethanol/water mixed solution system under mild conditions. The obtained rodlike particles were highly uniform in width (23 ± 3 nm), and its length could be tuned by adjusting the concentration of oxalic acid reactant. The nanorods materials show a promising electrorheological activity, of which ER efficiency was about 4 times higher that of granular CTP suspensions. The facile synthesis route may be regarded as a green chemistry method, and its novelty relies on the large-scale production of 1D CTP giant ER materials.

Preparation of uniform titania microspheres with good electrorheological performance and their size effect

Titania is a potential high-performance electrorheological (ER) material due to its relatively high dielectric constant and polarization ability. The size and shape of titania particles are critical factors influencing ER activity. In this paper, we have developed an acetic acid (AA) assisted sol–gel strategy for the synthesis of uniform titania microspheres with good ER effect. The diameter of the titania microspheres (from 420 to 240 nm) can be tuned by changing the amount of AA added. The facile route has the great potential in bulk synthesis of the titania based ER materials. Results from surface area, rheological, conductivity and dielectric properties measurements indicate that the enhanced ER performance is due to the combined effect of the increased polar molecules content and reduced particle size.

Fabrication of uniform core–shell structural calcium and titanium precipitation particles and enhanced electrorheological activities

A simple co-precipitation route was developed to synthesize uniform core-shell structured calcium and titanium precipitation (CTP) particles with ideal morphology and no aggregation. X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), transmission electron microscope (TEM), and interface tension/contact angle (CA) measurement were utilized to characterize the components, structure, morphology, and wettability of the SiO(2)-CTP materials. The obtained core-shell structural SiO(2)-CTP particles were well dispersed spherical nanoparticles with a narrow size distribution. The electrorheological (ER) properties were studied by the shear stress under various electric fields. The SiO(2) (2.3 wt%)-CTP ER fluid showed notable ER activity with a shear stress of about 109 kPa (at 5 kV mm(-1)), which outclassed the shear stress (65 kPa) of the CTP ER fluid. The ER properties of samples can be tuned by a few factors in the experimental process, such as the concentration of SiO(2) particles and citric acid, pointing out the great potential for application of this route in bulk synthesis of many other types of ER materials.

Size-controllable synthesis of monodispersed colloidal silica nanoparticles via hydrolysis of elemental silicon

A new method is presented for preparing monodisperse and uniform-size silica nanoparticles using a two-stage hydrolysis of silicon powder in aqueous medium. The influence of synthesis conditions including solution composition and temperature on the formation of silica nanoparticles were systematically investigated. The structure and morphology of the silica particles were characterized via transmission electron microscopy (TEM) and dynamic light scattering (DLS). Various-sized particles in the range 10-100 nm were synthesized. The size of the nanoparticles can be precisely controlled by using a facile regrowth procedure in the same reaction media.