Microwave-assisted rapid synthesis and characterization of CaF2 particles-filled cellulose nanocomposites in ionic liquid

• Cellulose/CaF2 nanocomposites were fabricated via microwave ionic liquid method.
• Heating modes, temperature and time affected morphology, property, crystallinity.
• Formation mechanism of cellulose-based nanocomposites was researched.
• This method was extended to the synthesis of cellulose/MgF2 nanocomposites.

In this article, we try to compound cellulose/alkali earth metal fluorides (MF2, M = Ca, Mg, Sr, Ba) nanocomposites via microwave-assisted ionic liquid method, wherein cellulose/CaF2 and cellulose/MgF2 were successfully synthesized through this method while cellulose/SrF2 and cellulose/BaF2 could not be synthesized. We focused on the synthesis of cellulose/CaF2 and investigated the influences of the different time and different temperature for the synthesis of cellulose/CaF2 nanocomposites. The influence of different heating methods such as oil-bath heating method was also studied. Ionic liquid ([Bmim][BF4]) was used for dissolving microcrystalline cellulose and providing the source of fluoride ionic and the alkali earth metal nitrate (Ca(NO3)2, Mg(NO3)2, Sr(NO3)2, and Ba(NO3)2) was used as the reaction initiator. They were investigated by X-ray powder diffraction (XRD), Fourier transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TG), derivative thermogravimetric (DTG), and energy-dispersive X-ray spectra (EDS). The different heating modes have influence on the morphology and property. The different temperature and heating time also have a certain influence on the morphology and crystallinity of calcium fluoride.