Synthesis of transparent dispersions of aluminium hydroxide nanoparticles

Abstract

Transparent dispersions of inorganic nanoparticles are attractive materials in many fields. However, a facile method for preparing such dispersions of aluminium hydroxide nanoparticles is yet to be realized. Here, we report a direct reactive method to prepare transparent dispersions of pseudo-boehmite nanoparticles (1 wt%) without any surface modification, and with an average particle size of 80 nm in length and 10 nm in width, as well as excellent optical transparency over 94% in the visible range. Furthermore, transparent dispersions of boehmite nanoparticles (1.5 wt%) were also achieved after an additional hydrothermal treatment. However, the optical transparency of dispersions decreased with the rise of hydrothermal temperature and the shape of particles changed from rhombs to hexagons. In particular, monodisperse hexagonal boehmite nanoplates with an average lateral size of 58 nm and a thickness of 12.5 nm were obtained at a hydrothermal temperature of 220 °C. The selectivity of crystal growth direction was speculated as the possible formation mechanism of these as-prepared aluminium hydroxide nanoparticles. Besides, two values of 19.6 wt% and 14.64 wt% were separately measured for the weight loss of pseudo-boehmite and boehmite nanoparticles after a continuous heating, indicating their potential flame-resistant applications in the fabrication of plastic electronics and optical devices with high transparency.

Surfactant-Free Aqueous Dispersions of Shape- and Size-Controlled Zirconia Colloidal Nanocrystal Clusters with Enhanced Photocatalytic Activity

“…In the past two decades, the preparation of colloidal nanoparticles with tunable size and shape is of increasing interest for their novel properties, which cannot be obtained using bulk materials. − However, recent research appears to be directed toward the controlled clustering of nanoparticle subunits into defined geometric arrangements. Clustering nanoparticles into secondary structures to form so-called colloidal nanoparticle clusters (CNCs) not only combines the size-dependent properties of individual nanoparticles but also makes use of the interactions between nanoparticle building blocks, generating collective properties, and novel functionalities absent in the initial nanoparticles. − Usually, the preparation strategy of CNCs can be divided into two categories: (i) a one-step route which refers to the synthesis of nanoparticles and their oriented attachment into CNCs in a single step; , and (ii) a two-step route which means the pre-preparation of nanoparticles as building kits and the subsequent clustering into CNCs via some methods, such as solvent evaporation, electrostatic attraction, spray drying, or interfacial tension. − Although the two-step route has the advantage of being more flexible and universal for generating highly configurable structures, the one-step route is more efficient and quicker.…”

Optimization and Characterization of Nano Aluminum Trihydrate-Based Flame-Retardant Materials in the Rotating Packed Bed Reactor

“…The interfacial bonding force is weak, so that the workability and physical mechanical properties of the composite with this flame retar- [27]. In addition, synthesis of ATH was explored recently by Chen et al [28] who obtained pseudo-boehmite nanoparticles with a direct precipitation method and the transparent dispersions of boehmite nanoparticles was obtained by a following hydrothermal treatment. The formation mechanism of ATH was also discussed in this paper.…”