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An innovative process to uniformly incorporate dispersed nanoscale ceramic inclusions within a polymer matrix was demonstrated. Micron‐sized high density polyethylene particles were coated with ultrathin alumina films by atomic layer deposition in a fluidized bed reactor at 77°C. The deposition of alumina on the polymer particle surface was confirmed by Fourier transform infrared spectroscopy and X‐ray photoelectron spectroscopy. Conformal coatings of alumina were confirmed by transmission electron microscopy and focused ion beam cross‐sectional scanning electron microscopy. The results of inductively coupled plasma atomic emission spectroscopy suggested that there was a nucleation period. The results of scanning electron microscopy, particle size distribution, and surface area of the uncoated and nanocoated particles showed that there was no aggregation of particles during the coating process. The coated polymer particles were extruded by a heated extruder at controlled temperatures. The successful dispersion of the crushed alumina shells in the polymer matrix following extrusion was confirmed using cross‐sectional transmission electron microscopy. The dispersion of alumina flakes can be controlled by varying the polymer particle size.

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A novel reactor designed to study the effects of continuous or controlled periodic illumination (CPI) on photocatalytic reactions was built and tested. The reactor uses immobilized films of TiO2 on the circular face of a disk. Rotating disk hydrodynamics provide uniform access to the catalyst surface. These coated disks rotate in a closed cell filled with the reagents at angular velocities ranging from 20 to 100 revolutions per minute (rev/min). A bank of black lamps provides uniform UV illumination to the disk surface. A mechanical shutter is used to provide the periodic illumination. This shutter can provide light or dark times as short as 100 ms and as long as minutes. To evaluate the performance of this reactor, the oxidation of formate ion (HCOO-) to CO2 and H2O was studied at various light intensities and a single light and dark time. As the light intensity was increased from 0.05 to 5.5 mW/cm2 the photoefficiency for continuous illumination experiments decreased from 80% to 5%. At a light time of 0.6 s and a dark time of 2.0 s and a light intensity of 5.5 mW/cm2, the photoefficiency increased from 5% during the continuous illumination experiments to 20% with CPI. However, at low light intensities (I < 0.5 mW/cm2), CPI did not effect the photoefficiency. Analysis of the results indicates that the reactor is oxygen diffusion-limited at light intensities above 0.5 mW/cm2 when air is used as the oxidant. At intensities below 0.3 mW/cm2, the reaction is photon limited and we are able to study the kinetics of the reaction. At light intensities between 0.3 and 0.5 mW/cm2, the reaction is controlled by both surface kinetics and diffusion limitations.