Poly(styrene butylacrylate) latex/nano-ZnO composites were prepared by blending poly(styrene butylacrylate) latex with a water slurry of nano-ZnO particles, and the effects of certain parameters, such as particle size, dispersant type, dispersing time and others, on the dispersibility, mechanical properties, ultraviolet (UV) shielding and near infrared (NIR) shielding were investigated with transmission electron microscopy (TEM), an Instron testing machine, dynamic mechanical analysis and ultraviolet-visiblenear infrared (UV-VIS-NIR) spectrophotometry. TEM observation showed that dispersants with long chains are better than those with short chains at enhancing the dispersibility of nano-ZnO particles in a matrix; extending dispersing time also improves the dispersibility of nano-ZnO particles in a matrix. Instron tests showed that the nanocomposite polymers embedded with nano-ZnO particles had much higher tensile strength than the corresponding composite polymers with micro-ZnO particles. As the nano-ZnO content increased, the temperature of glass transition (T g ) of the nanocomposite polymer embedded with 60 nm ZnO particles first increased then decreased, but 100 nm ZnO and microZnO particles seemed to have no influence on the T g of the composite polymers. The better dispersibility of nano-ZnO particles resulted in higher T g values. Increasing nano-ZnO content or dispersibility could enhance the UV shielding properties of the nanocomposite polymers, and 60 nm ZnO particles could more effectively shield UV rays than 100 nm ZnO particles. Micro-ZnO particles basically had no effect on the UV absorbance of the composite polymers. A blueshift phenomenon was observed at 365 nm when nano-ZnO particles were present in the nanocomposite polymers. NIR analysis indicated that as nano-ZnO content increased, the NIR shielding of the nanocomposite polymers increased, but the NIR shielding properties seemed to be more influenced by particle size than by the nano-effect.

Acrylic/nano‐silica composite latexes were prepared by blending via high shear stirring (SS) or ball milling (BM) and in situ polymerization (IS). For comparison, composites filled with micro‐silica were also prepared. The mechanical and optical properties of the polymers formed by the composite latex filled with nano‐ or micro‐silica were investigated using an Instron testing machine, by dynamic mechanical analysis, ultraviolet–visible spectrophotometry and transmission electron micrography. The results showed that SS and BM methods could obtain better nanocomposite latex and polymers than the IS method, characterized by better dispersion of nanoparticles, higher tensile strength and Tg for SS and BM than for IS. The increase in absorbance and reduction in transmittance of UV (290–400 nm wavelength) were observed as nano‐silica content increased, whereas the UV absorbance or transmittance basically were kept unchanged for the composites filled with micro‐silica.© 2002 Society of Chemical Industry

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