Photocontrolled Release of Dye Molecules from Azobenzene-Modified Nanocomposite Particles

Photocontrolled Release of Dye Molecules from Azobenzene-Modified Nanocomposite Particles 

In the release process, the dye-filled particles were dispersed in 5mL EtOH. One sample was stirred under UV light irradiation and the other was stirred in the dark. After filtration, the concentration of the OBN molecules released into EtOH was determined by the absorbance (A) of the solution at Amax (644 nm) using UV/visible spectroscopy. The release data of the two samples are shown in Fig. 13.20. There are two factors influencing the release rate the effective pore size 

A simple model was developed to evaluate the effective diffusivity of OBN in the photoresponsive nanocomposite particles. In this model, it was assumed that the particles had uniform size and each particle was surrounded symmetrically by an equal volume of solution (volume of solution/number of particles). Although the particles had a wide size distribution, it is reasonable to use the average particle size to evaluate the effective diffusivity. 

Using an average particle diameter of 2 pm and a Ds (diffusion coefficient of OBN in solution) value of 10 m s, the effective diffusion coefficients in the dark 

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