Surface Modification of Nanomaterials for Application in Polymer Nanocomposites: An Overview

In recent years, advanced nanocomposite materials have been widely used in a large number of commercially valuable industrial applications such as in automobile, marine coatings, aerospace, and construction industries. The nanocomposites are made up of organic polymers and inorganic nanomaterials using different processing techniques. For example, metal, metal oxide, and carbon-based nanomaterials have been widely used in the preparation of hybrid polymer nanocomposites. The nanocomposites are a new class of advanced materials exhibiting excellent properties compared to those of virgin polymers [1]. Nanomaterials have the ability to improve the properties of polymeric materials. In order to avoid agglomeration and insufficient dispersion of nanomaterials in polymer matrices, the surfaces of the nanomaterials are modified with some organic functionalities. Without surface modification, the unmodified nanomaterials reduce the properties of polymer nanocomposites [2, 3]. Owing to the excellent interfacial interaction between the surface of the nanomaterials and polymers, Surface-modified nanomaterials (SMNs) have attracted a great deal of attention compared to unmodified nanomaterials [4]. The surface functionalization of nanomaterials is carried out with a variety of organic functional groups such as alcohols, thiols, sulfonic, carboxylic acids, and amines. Numerous methods have been employed in the process of surface modification of nanomaterials, which is based on (i) copolymerization of functional organosilanes, macromonomers, and metal alkoxides, (ii) functionalization of organic components within sol–gel-derived silica or metallic oxides, (iii) organic functionalization of nanotubes, nanoclays, or other compounds with lamellar structures, and so on [5]. SMNs that have been reinforced into polymer matrices result superior hybrid nanocomposites, which possess light weight and high strength. The SMNs enhance the mechanical, rheological, optical, electrical, thermal, and flame retardancy properties of the polymer matrices [6, 7]. SMN-reinforced polymeric