In this paper, a series of colloidal polymers with various Tg, composition, and sphere size were synthesized by surfactant-free emulsion polymerization and dispersion polymerization methods and then blended with colloidal silica particles to obtain polymer/silica nanocomposite latexes. When these nanocomposite latexes were forced dry at high temperature (e.g., 110℃) for 2h, a three-dimensional ordered porous structure was directly obtained. Neither complex processes nor removal of any templates like in a templating method is needed. These ordered pores should form from the top surface and then propagate layer by layer from the top surface to substrate.

Highly crystalline and dispersible zirconia nanoparticles, ex situ synthesized from a solvothermal reaction of zirconium(IV) isopropoxide isopropanol complex in benzyl alcohol, were functionalized with 3-(trimethoxysilyl)propyl methacrylate and blended with UV-curable urethane-acrylate formulations to fabricate poly(urethane-acrylate)/zirconia (PUA/ZrO2) nanocomposite coatings. A critical ZrO2 concentration of 20 wt% was observed for the evolutions of both the structure and properties of the nanocomposites as a function of ZrO2 content. Below the critical concentration, completely transparent nanocomposite film was obtained and the nanocomposites exhibited increasing final carbon-carbon double bond conversion, refractive index, hardness, elastic modulus, and thermal stability as ZrO2 content increased. However, serious agglomeration of ZrO2 nanoparticles occurred at 25 wt% of ZrO2, which decreased final conversion, transparency and hardness, and thermal stability of the nanocomposite film. These results clearly reveal that the performance of UV-curable anocomposites is strongly dependent on the dispersion of nanoparticles.

The dispersion behavior of crystalline zirconia nanoparticles with a diameter of 3.8nm, synthesized from zirconium-(IV) isopropoxide and benzyl alcohol in tetrahydrofurane (THF), methyl methacrylate (MMA), and styrene (St), was investigated using 3-(trimethoxysilyl)propyl methacrylate (MPS), ethyl 3,4-dihydroxycinnamate (EDHC), allylmalonic acid (AMA), and trimethylolpropane mono allyl ether (TMPMA) as ligating stabilizers containing polymerizable vinyl groups. Analytical ultracentrifugation (AUC) and transmission electron microscopy (TEM) analyses prove that the as-synthesized wet zirconia nanoparticles can be dispersed inTHFwithout any agglomeration when using the appropriate ligand concentrations. Surface-adsorbed water, if intentionally introduced during the washing step, and also air humidity seriously deteriorate their dispersibility. These results suggest that the excellent dispersibility of the zirconia nanoparticles is a direct consequence of the nonaqueous synthesis approach. Fourier transform infrared spectra (FTIR) and thermogravimetric analysis (TGA) illustrate that MPS, EDHC, and AMA are chemically attached but TMPMA is physically attached to the surface of the zirconia nanoparticles. Transparent dispersions of zirconia nanoparticles can also be prepared in MMA with the help of MPS, EHDC, and AMA or in St with MPS and TMPMA, opening a promising pathway for the direct application of zirconia nanoparticles in polymer-based nanocomposites.

Zirconia (ZrO2) nanocrystals, synthesized from zirconium(IV) isopropoxide isopropanol complex and benzyl alcohol, were dispersed and functionalized in organic solvents using three kinds of bifunctional silane coupling agents (SCAs), 3-glycidoxypropyltrimethoxysilane (GPTMS), 3-aminopropyltriethoxysilane (APTES), and 3-isocyanatopropyltriethoxysilane (IPTES). Completely transparent ZrO2 dispersions were achieved in tetrahydrofuran (THF) with all three SCAs, in pyridine and toluene with APTES and IPTES, and in N,N-dimethylformamide with IPTES. Dynamic laser scattering (DLS) measurements and high-resolution transmission electron microscopical (HRTEM) observation indicated that the ZrO2 nanocrystals are dispersed on a primary particle size level. Fourier transform infrared spectroscopy, solid-state 13C-and 29Si NMR spectroscopy, and thermogravimetric analysis demonstrated that all three SCAs are chemically attached to the surface of the ZrO2 nanoparticles, however, in different bonding modes. Except for GPTMS/ ZrO2/THF dispersion and IPTES/ZrO2/pyridine dispersion, all other transparent dispersions have poor long-term stability. The increasing polarity, due to high amount of APTES attached and high hydrolysis and condensation degree of the bonded APTES, and the aggregation, due to interparticle coupling via the bonded triethoxysilyl group, are the causes of the poor long-term stability for the ZrO2 dispersions with APTES and IPTES, respectively. Nevertheless, the APTES-functionalized ZrO2 precipitates can be deagglomerated in water to get a stable and transparent aqueous ZrO2 dispersion via addition of a little hydrochloric acid.

The de-agglomeration and dispersion of nano-TiO2 powder is little reported, although nano-TiO2 powder has been widely used due to its unique optical properties. In this study, an agitator bead mill (MiniZETA 03E, Netzsch) accompanied with an ultrasonicator was employed to de-agglomerate the nano-TiO2 powder in butyl acetate, and the effects of ultrasonic pretreatment, dispersant dosage, agitation speed, solid content of TiO2 suspension, and bead diameter were systemically investigated. It is found that ultrasonic pretreatment leads to short grinding time to reach the limiting fineness, low specific energy input, and small limiting mean size. All other technical parameters have also some influence on the limiting fineness and grinding time. However, the former strongly depends on agitation speed while the latter on both agitation speed and dispersant dosage. A solvent-borne nano-TiO2 suspension with limiting mean size of 110 nm can be successfully result under the optimal technical conditions and showed excellent UV-shielding property and transparence when it was incorporated into polyester/melamine coatings.