d


6.2.2.1 Optical measurements results

 Figure 6-6 represents the UV-vis absorption spectra of iodine in various aqueous and

organic environments. The measurements were recorded after addition of 1mL of a saturated

iodine aqueous solution to given amounts of either nanocapsule or ethyl butyrate solutions. The

large signal shift toward lower wavelengths (blue shift) compared to the spectrum in water

qualitatively indicates that the chemical environment of iodine significantly changes (becomes

more hydrophobic) after addition of the nanocapsule solution, and that therefore a consequent

uptake in the hydrophobic nanocapsule core took place. However, test experiments have also

been performed on a Tween-80 aqueous solution to appreciate the influence of this compound in

the process. The overlap of the iodine UV-vis curves in the presence of nanocapsules and

Tween- 80 i ndi cate s that Tween- 80 alone was al so cap ab le of ab sorb ing/encap sul ati ng i odi ne i n

its hydrophobic micellar core (Cls chains), so that it is not very clear at this point if a separate

layer of Tween-80 in the nanocapsules, Tween-80 dissolved in the organic solvent core, or the

organic solvent core itself is effective in retaining iodine.


 3010 40)0 500] 600 700]

 Wavelength (nm)

Figure 6-6. UV-vis absorption spectra of iodine in water solution (a), in nanocapsule solution (b),
 in Tween-80 aqueous solution (c), and in ethyl butyrate solution (d).


0.2