Graphene Oxide and Reduced Graphene Oxide as Nanofillers …
115
suspension. Likewise, Xu et al. fabricated a loaded GO–TiO 2 membrane through
vacuum filtration of GO–TiO 2 composite nanosheets [40, 43]. A variety of polymer–
GO composites, such as poly (vinyl acetate)–GO, polyurethane–GO, Nafion–GO,
poly (vinyl alcohol)–GO, polybenzimidazole–GO, and poly(allylamine)/GO have
been thoroughly investigated [44–47].
In summary, according to literature reports, it is expected that the polymer–
GO/rGO nanocomposite membranes could be an outstanding technology for water
purification. Some of these interesting works are reviewed in this chapter as a reflection for future works. This chapter will also present the fabrication methods and
characterization techniques of polymer–GO/rGO composite membranes.
2 Preparation Methods of Polymer–GO/rGO
Nanocomposite
GO surface functional groups, such as epoxide, hydroxyl, carbonyl, and carboxyl
groups, make it as a potential candidate for preparing nanocomposites [48, 49]. Most
of polymer–GO/rGO composites have been prepared by three common procedures
of solvent processing, in situ polymerization, and melt processing [50] and, also,
other new preparation methods, such as Pickering emulsions and spin coating which
are investigated in the next sections.
2.1 Solvent Processing
Among the reported methods for synthesizing polymer–GO/rGO nanocomposites,
solvent processing is one of the most current procedures, because of the well dispersion of GO in many solvents [51]. This method is based on a solvent system in which
the polymer is solubilized and graphene or modified graphene layers are allowed
to swell [52]. GO is directly dispersed in water or various organic solvents such
as chloroform, acetone, toluene, dimethylformamide (DMF), and tetrahydrofuran
(THF). The sp
2 carbon network of GO sheets can be recovered during the dispersion
by reducing the GO sheets using specific solvent [53–55]. After mixing GO and
polymer with solvent, the polymer–rGO composites are prepared through reducing
GO either at the same time as solvent mixing or after the blending of polymer and
GO. Up to now, a variety of polymer–rGO composites have been prepared through
this approach [51, 56–59].
Uniform dispersion of graphene/GO/rGO in the solvent solution is important
before mixing them with the polymer matrix. For instance, Zhang et al. [60] homogeneously dispersed the rGO in organic media without the addition of complex
dispersing agents or the requirement of functionalized GO. In this experiment, the
aqueous colloids of rGO sheets were prepared in an alkaline solution. The produced
115
suspension. Likewise, Xu et al. fabricated a loaded GO–TiO 2 membrane through
vacuum filtration of GO–TiO 2 composite nanosheets [40, 43]. A variety of polymer–
GO composites, such as poly (vinyl acetate)–GO, polyurethane–GO, Nafion–GO,
poly (vinyl alcohol)–GO, polybenzimidazole–GO, and poly(allylamine)/GO have
been thoroughly investigated [44–47].
In summary, according to literature reports, it is expected that the polymer–
GO/rGO nanocomposite membranes could be an outstanding technology for water
purification. Some of these interesting works are reviewed in this chapter as a reflection for future works. This chapter will also present the fabrication methods and
characterization techniques of polymer–GO/rGO composite membranes.
2 Preparation Methods of Polymer–GO/rGO
Nanocomposite
GO surface functional groups, such as epoxide, hydroxyl, carbonyl, and carboxyl
groups, make it as a potential candidate for preparing nanocomposites [48, 49]. Most
of polymer–GO/rGO composites have been prepared by three common procedures
of solvent processing, in situ polymerization, and melt processing [50] and, also,
other new preparation methods, such as Pickering emulsions and spin coating which
are investigated in the next sections.
2.1 Solvent Processing
Among the reported methods for synthesizing polymer–GO/rGO nanocomposites,
solvent processing is one of the most current procedures, because of the well dispersion of GO in many solvents [51]. This method is based on a solvent system in which
the polymer is solubilized and graphene or modified graphene layers are allowed
to swell [52]. GO is directly dispersed in water or various organic solvents such
as chloroform, acetone, toluene, dimethylformamide (DMF), and tetrahydrofuran
(THF). The sp
2 carbon network of GO sheets can be recovered during the dispersion
by reducing the GO sheets using specific solvent [53–55]. After mixing GO and
polymer with solvent, the polymer–rGO composites are prepared through reducing
GO either at the same time as solvent mixing or after the blending of polymer and
GO. Up to now, a variety of polymer–rGO composites have been prepared through
this approach [51, 56–59].
Uniform dispersion of graphene/GO/rGO in the solvent solution is important
before mixing them with the polymer matrix. For instance, Zhang et al. [60] homogeneously dispersed the rGO in organic media without the addition of complex
dispersing agents or the requirement of functionalized GO. In this experiment, the
aqueous colloids of rGO sheets were prepared in an alkaline solution. The produced