ABSTRACT: Highly flexible, transparent, and luminescent
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