Cellulose–Polyvinyl Alcohol–Nano-TiO2 Hybrid Nanocomposite: Thermal, Optical, and Antimicrobial Properties against Pathogenic Bacteria

ABSTRACT Cellulose fiber-reinforced composite has received great attention due to the high strength, stiffness, biodegradability, and renewability of the excellent natural biomaterials. Cellulose nanofibers for the development of organic–inorganic hybrid composite is relatively new filed of research. Cellulose macro and nanofibers can be used as reinforcement in the hybrid composite because of improved mechanical, thermal, optical, electrical, morphological, and biological properties. The hybrid nanocomposites were synthesized by an in situ sol–gel process in the presence of coupling agent. The sol–gel process has definitely proven its potential by providing the synthesis of various functional organic–inorganic hybrid nanocomposites through an in situ sol–gel process. The hybrid nanocomposites have been prompted by the ability to control the morphology of final materials. The photoluminescence spectral studies indicate that the emission shifts toward higher wavelength (326–532 nm) accompanied by a reduction in impurity centers with increasing concentration of poly(vinyl alcohol)–TiO2 and hybrid nanocomposite. The final nanostructured TiO2 hybrid nanocomposites with particle size ranging from 0.32 to 20 nm were characterized by Field -emission transmission electron microscopy (FE-TEM) analysis. Furthermore, cellulose–poly(vinyl alcohol)–nano-TiO2 hybrid composite was characterized by Fourier transform infrared, X-ray diffraction, UV, Thermogravimetric analysis (TGA), Differential scanning calorimetry (DSC), FE-SEM–EDX, Field-emission scanning electron microscopy (FE-SEM), and FE-TEM analysis. The different analysis results of the hybrid composite indicate the optical transparency, optical properties, Tg, crystallinity, thermal stability, and controlled morphology of hybrid nanocrystalline composites. Finally, the cellulose–poly(vinyl alcohol)—nano-TiO2 hybrid nanocomposites were tested against pathogens such as Gram-positive Bacteria Bacillus cereus and Gram-negative Escherichia coli for antimicrobial activity. These results show that the hybrid composite exhibited excellent antimicrobial properties against pathogens. GRAPHICAL ABSTRACT