Nanocomposites of Cellulose with Up-Conversion Phosphors for Photonics: Synthesis, Structure, Optical Properties

The luminescent hydrophobic composite films based on nanocellulose matrix with up-conversion SrF2 :Ho or CaF2 :Ho particles have been synthesized and studied by X-ray diffraction, electron microscopy and optical spectroscopy techniques. The size distributions of cellulose nanoparticles in homogeneous aqueous dispersions of cellulose nanocrystals (CNC), cellulose nanofibrils (CNF) and TEMPO-oxidized nanocellulose (TOCN) were determined. Flexible, durable, translucent composite films were obtained by molding from the said CNC/CNF or TOCN suspensions and up-conversion particles. Optical transmission, spectral-luminescent properties, surface morphology, degree of polymerization, structure and crystallinity index of nanocellulose, surface hydrophobization conditions of the said CNC/CNF or TOCN composite films have been determined. The manufactured up-conversion hydrophobic composite films can be utilized as potential photonics materials (in particular, materials for the visualization of near-infrared laser radiation), as luminescent labels, luminescent detectors, etc.