Alginate-guided size and morphology-controlled synthesis of MnO2 nanoflakes

This work reports the morphology, crystal size, and shape variations of nanoparticles, including manganese dioxide- MnO2 during in situ synthesis in biopolymer. In this context, stable nanocomposite based on sodium alginate (Alg)- MnO2 were produced in different solutions by changing the reaction conditions. Then the host polymer, Alg was removed via calcination to obtain neat nanoflakes. The chemical, thermal, morphology, and structural properties as well as porosity of pure MnO2, Alg-MnO2, and calcinated products were investigated using scanning electron microscopy (SEM), Transmission electron microscopy (TEM), X?ray diffraction (XRD), thermogravimetric analysis (TGA), differential thermal analysis (DTA), Brunauer-Emmett-Teller (BET), and Fourier transform infrared spectroscopy (FT-IR). It was clearly demonstrated that the presence different solvents, polymer, and the pH variations affected noticeably on the crystal structures of the samples. Additionally, nanorods monodispersed particles with length and width around 200 and 7-10 nm were produced without Alg in isopropanol. Whereas, in the same condition, the morphology of MnO2 changed to nanoflakes structures in the existence of Alg and size diminished to quarter (50 nm)of the pristine material. A further decrease in the nanoflake size was observed in the neural pH, acidic and basic environmental conditions with Alg route.