Synthesis and characterization of carbon nanoparticle/PVA/ chitosan for security ink applications

Security ink using a carbon nanoparticle (C-dot)/PVA/chitosan-composite-based material has been successfully synthesized. The C-dot powder was prepared using a urea pyrolysis method. The precursors were synthesized using urea ((NH 2 ) 2 CO, Mw = 60.07 g mol −1 ) and citric acid (C 6 H 8 O 7 ∙H 2 O, Mw = 210.14 g mol −1 ) as the fuel and carbon sources, respectively. The C-dots were prepared by heating the precursor solution at 250 °C for 90 min. The security ink was fabricated using C-dots, polyvinyl alcohol (PVA, (CH 2 CH(OH)) n , with Mw = ~20 000 g mol −1 ) and chitosan as the dyes, resins and binders, respectively. The morphology and optical properties of the security ink were measured using SEM and EDX, a PL spectrometer and UV–vis spectroscopy. The viscosity properties of the security ink were measured using a viscometer. The characterization showed that the C-dots have a monodisperse particle size, a tetragonal structure and absorption spectra in the UV light region. It is shown that the PVA:chitosan concentration has a significant effect on the viscosity properties, so the viscosity is optimized for the security ink. In addition, the security ink was studied using a commercial printer, and the results show a good quality blue emission (450 nm) appearing under UV light exposure at 365 nm. The security ink C-dot/PVA/chitosan composite has potential applications in security, panel display, optoelectronic and optical devices on an industrial scale.