CdSe/ZnS QDs embedded in cellulose triacetate films with hydrophilic surfaces

Quantum dot (QD)/polymer composite films were prepared by solvent casting suspensions of CdSe/ZnS semiconductor nanoparticles in cellulose triacetate (CTA) solution. The common solubilities of the organic ligands capping the QDs and of the polymer permitted the direct addition of QDs into the CTA casting solution. The films were robust, with typical thicknesses of 0.05 mm, and possessed the optical properties characteristic of QDs. The emission wavelength of the QD/CTA films shifted with time but eventually reverted toward its original value. This effect was attributed to changes in humidity and solvent content of the films. Transmission electron microscopy (TEM) images of QD/CTA films revealed that the QDs were well-dispersed within the CTA film matrix. The selective alkaline hydrolysis of QD/CTA films in 0.1 M NaOH over 24 h resulted in the surface conversion of CTA to regenerated cellulose. X-ray photoelectron spectroscopy (XPS) and attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) were employed to study the surface composition of the films and transmission mode Fourier transform infrared spectroscopy was used to study the bulk composition. Optical properties of the films were probed both before and after the hydrolysis reaction using fluorescence spectroscopy and were found generally unaltered. The cellulose surfaces of the alkaline-treated films should allow facile incorporation into paper sheets.