Waterborne adhesives are extremely environment-friendly but unfortunately deficient in mechanical properties. In this article, nanosilica, stemming from tetraethyl orthosilicate (TEOS), silica sol, and/or fumed silica powder, was employed to reinforce the waterborne silylated polyether adhesives. Effects of TEOS content, silica sol content, and the type and content of fumed silica on the shear strength of the adhesive were investigated using a scanning electronic microscope and an electronic instron tester and the strengthening mechanisms of different silica source were discussed. All the shear strengths of silylated polyether adhesives first increased and then decreased as TEOS content, silica sol content or fumed silica content increased. Colloidal silica particles was less efficient than fumed silica particles for reinforcing the polyether adhesive but can increase the shear strength of hydrophobic fumed silica embedded adhesive. Comparing the adhesives with the hydrophilic fumed silica (HS-5) or the extremely hydrophobic fumed silica (TS-720), the adhesive with moderate hydrophobic fumed silica (TS-610) had the highest shear strength. The maximal shear strength of 2.5 MPa was achieved when TEOS, silica sol, and fumed silica were combined. It seemed that TEOS, silica sol, and fumed silica played crosslinking (with polyether chain), dispersing (for fumed silica), and reinforcing roles on waterborne adhesive, respectively. This reinforcing mechanism opened a new way to fabricate waterborne adhesives (or coatings) with high performances.

WO3·H2O nanotubes are successfully synthesized with the aid of intercalated polyaniline (PANI) under relatively mild conditions. More interestingly, the WO3·H2O nanotubes have a rectangular cross-section structure formed through a rolling mechanism. Scanning electron microscopy, transmission electron microscopy, X-ray diffraction, thermogravimetric analysis, Fourier-transform infrared analysis, UV-vis-near-IR spectroscopy, selected-area electron diffraction, and vibrating-sample magnetometry analysis are employed to characterize the morphology, structure, and properties of the nanotubes.

The colloidal silica particles were first modified with methyltriethoxylsilane and methacryloxypropyltrimethoxysilane, respectively, then embedded into acrylic based polyurethane using blending method or in situ method. The effects of the silane couple agent type, modified silica content and preparation method on the redispersibility of silica particles and mechanical properties of polyurethane coats were investigated using 29Si NMR, TGA, FT-IR, particle size analyzer, SEM, DMA and Instron machine. It was found that different silane couple agent and preparation method had obvious influences on the redispersibility and mechanical properties. © 2006 Elsevier B.V. All rights reserved.

The photopolymerization kinetics of poly(urethane-acrylate)/zirconia (PUA/ZrO2) nanocomposite coatings were monitored on-line and in-real-time with microdielectrometry (DEA) in terms of logarithmic ion viscosity (log). For comparison, real-time infrared spectroscopy (RTIR) was also employed to determine the evolution of C=C bond conversion (C) with irradiation time (t). Coupling log-t curves with C-t curves indicates that the relationship between log and C for all the coatings with different formulations (i.e. the type of photoinitiator, ZrO2 content) and curing condition (i.e. irradiation intensity) can be correlated to one linear equation at conversion less than ∼85%. Moreover, DEA monitoring was longer time to reach polymerization equilibrium than RTIR for those cases with high limited conversion, suggesting that the former is more sensitive to C=C bond conversion than RTIR at high conversion stage (C>∼85%). DEA monitoring on the photopolymerization kinetics of PUA/ZrO2 coatings as a function of various parameters further demonstrates that DEA results are reliable and reasonable to conventional radical photopolymerization. It is believed that DEA technique will be useful not only on the optimization of curing condition but also for the formulation of UV-curable coatings.

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.