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A seeded surfactant-free methyl methacrylate emulsion polymerization is employed to prepare core–shell particles with predetermined size and narrow size distribution. The particle size is determined by the ratio between methyl methacrylate (MMA, shell) and polytetrafluoroethylene (PTFE, core). Monodisperse particles in the 100–350 nm range are obtained. These particles are used to grow colloidal photonic crystals (opals) of very high optical quality, thus indirectly demonstrating the excellent control of microbead size distribution achieved by this preparation technique. The optical properties of the opals are investigated by means of reflectance and polarized-angle-resolved transmittance spectroscopies. These data provide a rough determination of the effective refractive index of the system, which is favorably compared with values obtained by simple effective medium models. Copyright © 2012 Society of Chemical Industry

A new version of the penetration test for mortars of historical masonry is based on the idea of “static” penetration. The pin is driven at constant velocity by a stepper motor controlled by a computer. The result of the test is the penetration load as function of the penetration depth. The penetrometer has been tested on masonry walls characterized by decayed mortar with poor cohesion. The results are correlated with those of a previous percussion penetration test.

We report on the control of spontaneous emission in flexible polymer 1D photonic crystal cavities fabricated by spin coating having a layer of poly(9,9-dioctylfluorenyl-2,7-diyl-co-1,4-benzo-(2,1′-3)-thiadiazole) (F8BT) as an active material. The optical properties of these full-polymer photonic crystals are systematically investigated by means of polarized angular-resolved transmittance and photoluminescence spectral measurements. We demonstrate strong directional emission enhancement when the emitter is located in the defect layer and resonantly coupled to the microcavity mode. The experimental results can be successfully reproduced with different theoretical optical models.

We report on the fabrication and full optical characterization of flexible full plastic one-dimensional photonic crystal cavities. We demonstrate strong directional emission enhancement when the emitting layer is resonantly coupled to the cavity mode.