Ultrasonic-assisted melt blending for polyvinyl alcohol/carbon dots luminescent flexible films

Carbon dots (C-dots) are small carbon nanoparticles and demonstrated various unique properties such as excellent photoluminescence properties. Hence, this property made the C-dots as the most promising fluorescent nanomaterial in various applications. In this study, we have successfully synthesized C-dots directly from the inner cassava peels using a microwave method with various growth time for 20, 40 and 60 min. After that, the as prepared C-dots solution would be composited with poly(vinyl alcohol) (PVA) solution using ultrasonic-assisted melt blending technique to prepared PVA/C-dots luminescent flexible films. The optical properties of C-dots solution, PVA/C-dots solution, and PVA/C-dots films are investigated in detail to observe the ability of the sample to maintain their optical properties when the obtained C-dots are prepared in a different phase. It was found that the fluorescence intensity (FL) of C-dots solution, PVA/C-dots solution, and PVA/C-dots considerably different each other. The highest fluorescence intensity was found when the C-dot was prepared as PVA/C-dots luminescent flexible films. Meanwhile, the lowest fluorescence intensity was found in pure C-dots without the addition of PVA. Interestingly, the absorbance of the sample was found to decrease when the C-dots prepared as PVA/C-dots films. Furthermore, C-dots solution was found to be homogeneous dispersed in PVA matrix due to the formation of hydrogen bonds between C-dots and PVA in PVA/C-dots film. Owing to their stable light emission and excellent optical properties indicate that C-dots from cassava peel have potential to be used in various applications.