**2.1 Solution blending of nanocomposites**

Solution blending is a common technique for fabrication of polymeric nanocomposites because it is both amenable for various sizes and effectiveness. The solution blending includes three steps: dispersion of nanoparticles in a solvent, mixing with the polymer solution at effective temperature, and finally recover the composite after precipitation or casting the film. Solution-based casting methods provide an advantage through low viscosities, which facilitate mixing and dispersion of the nanoparticles. Many studies have used these methods for processing both thermoset and thermoplastic polymers.

As mentioned earlier, it is difficult to disperse nanoparticles in solvents by simple stirring. The instruments such as ultrasonicator are suitable for making metastable suspensions of reinforcing filler/polymer mixtures in solvents. It is necessary to consider that ultrasonication for a long time affects the nanoparticles. When using solution blending, nanoparticles tend to agglomerate during slow solvent evaporation, leading to inhomogeneous distribution of the nanoparticles in the polymer matrix.
