Soft adhesives require an optimum balance of viscous and elastic properties. Adhesion is poor when the material is either too solidlike or too liquidlike. The ability to switch tack adhesion off at a desired time has many applications, such as in recycling, disassembly of electronics, and painless removal of wound dressings. Here, we describe a new strategy to switch off the tack adhesion in a model nanocomposite adhesive in which temperature is the trigger. The nanocomposite comprises hard methacrylic nanoparticles blended with a colloidal dispersion of soft copolymer particles. At relatively low volume fractions, the nanoparticles (50 nm diameter) accumulate near the film surface, where they pack around the larger soft particles (270 nm). The viscoelasticity of the nanocomposite is adjusted via the nanoparticle concentration. When the nanocomposite is heated above the glass transition temperature of the nanoparticles (T g = 130 °C), they sinter together to create a rigid network that raises the elastic modulus at room temperature. The tackiness is switched off. Intense infrared radiation is used to heat the nanocomposites, leading to a fast temperature rise. Tack adhesion is switched off within 30 s in optimized compositions. These one-way switchable adhesives have the potential to be patterned through localized heating.

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The influence of Quercus rotundifolia trees on precipitation chemistry, soil physical and chemical characteristics, light, nutrient and water availability and biomass production of the understorey was studied in a "montado" at Évora (southern Portugal). Ca and K were added to the soil by throughfall (21.05 and 38.49 kg/ha, respectively) and gross rainfall (3.49 and 3.98 kg/ha). Thickness of the soil organic layer and nutrient availability decreased with the distance from the tree trunk and were higher in ungrazed areas. Soil temperature was higher in areas without canopy, especially in winter. Soil moisture tended to decrease and refill faster in areas without canopy influence. PAR (photosynthetic active radiation) was intercepted around 75 to 90% by the canopy depending on the time of the year, and showed significant diurnal differences between inside and outside the canopy. Biomass production of the herbaceous layer responded more to water and fertilizer in the areas outside the tree canopy and without artificial shading than under the canopy. However, when the rate between the distinct biomass and the control was calculated, the response to water was more efficient under the canopy for the three treatments in the second year.

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