nanofibrillated cellulose (NFC) nanopaper with heterogeneous

network, functionalized by rare-earth up-converting

luminescent nanoparticles (UCNPs), was rapidly synthesized

by using a moderate pressure extrusion paper?making process.

NFC was successfully prepared from garlic skin using an

efficient extraction approach combined with high frequency

ultrasonication and high pressure homogenization after

removing the noncellulosic components. An efficient epoxidation treatment was carried out to enhance the activity of the

UCNPs (NaYF4:Yb,Er) with oleic acid ligand capped on the surface. The UCNPs after epoxidation then reacted with NFC in

aqueous medium to form UCNP-grafted NFC nanocomposite (NFC?UCNP) suspensions at ambient temperature. Through

the paper-making process, the assembled fluorescent NFC?UCNP hybrid nanopaper exhibits excellent properties, including high

transparency, strong up?conversion luminescence, and good flexibility. The obtained hybrid nanopaper was characterized by

transmission electron microscopy (TEM), atomic force microscope (AFM), Fourier transform infrared spectroscopy (FTIR),

field emission-scanning electron microscope (FE-SEM), up?conversion luminescence (UCL) spectrum, and ultraviolet and

visible (UV?vis) spectrophotometer. The experimental results demonstrate that the UCNPs have been successfully grafted to

the NFC matrix with heterogeneous network. And the superiorly optical transparent and luminescent properties of the

nanopaper mainly depend on the ratio of UCNPs to NFC. Of importance here is that, NFC and UCNPs afford the nanopaper a

prospective candidate for multimodal anti-counterfeiting, sensors, and ion probes applications.

KEYWORDS: nanofibrillated cellulose, luminescent nanopaper, garlic skin, rare-earth up-converting nanoparticles, extrusion