8.3 Materials and Methodology
8.3.1 Preparation Methods
The preparation of the polymer nanocomposites is done by various methods, such as
solution cast technique, in situ polymerization technique, melt intercalation technique, spin coating technique, hot press technique, and dip coating technique.
Solution Cast Technique
It is the traditional method and preferred due to its ease of fabrication and produces
polymer film from various thicknesses (50–300 μm). First of all, the specified
amount of the polymer host is dissolved in the appropriate solvent by continuous
stirring. Then the appropriate salt content is added to the homogenous polymer
matrix and again stirred till a homogenous and transparent solution is obtained. Now,
to prepare the polymer nanocomposite, firstly, the nanoparticle is added in a solvent,
and ultrasonication is performed for better dispersion. Then the obtained solution is
added to the polymer–salt solution and stirred till a homogenous solution is obtained.
Finally, the viscous solution is casted in the petri dish and kept at room temperature
for evaporation of the solvent and then kept in a vacuum oven to completely remove
the residual solvent, and film is peeled off from petri dish (Arya and Sharma 2018).
The obtained film is kept in a desiccator with silica gel for further characterization
and moisture prevention. For high-quality film, the solvent must be free from water
content and should dissolve the polymer, salt, and nanoparticle (Karuppasamy et al.
2015).
Spin Coating
This method is almost identical to the solution cast technique. The key advantages of
spin coating technique are simplicity and relative ease of preparation and produce
uniform films from a few nanometers to a few microns in thickness. In this
technique, a small amount of solution is dropped on a substrate and kept on the
spin coater which can be rotated at desired speed. The centripetal acceleration
spreads the mixture on a substrate followed by heating to evaporate the solvent.
One point that must be taken care of is that the substrate spinning axis must be
perpendicular to the substrate which is to be coated. The thickness of the film is
influenced by (i) viscosity of mixture, (ii) concentration of mixture, (iii) speed of
rotation, and (iv) spin time. However, this method is advantageous only for low
viscosity mixture not for too high viscosity mixture. For a gel mixture, the spin
coater rotation is not enough to spread the mixture droplet to form thin film (Park
et al. 2006; Krebs 2009).
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A. Arya and A. L. Sharma
8.3.1 Preparation Methods
The preparation of the polymer nanocomposites is done by various methods, such as
solution cast technique, in situ polymerization technique, melt intercalation technique, spin coating technique, hot press technique, and dip coating technique.
Solution Cast Technique
It is the traditional method and preferred due to its ease of fabrication and produces
polymer film from various thicknesses (50–300 μm). First of all, the specified
amount of the polymer host is dissolved in the appropriate solvent by continuous
stirring. Then the appropriate salt content is added to the homogenous polymer
matrix and again stirred till a homogenous and transparent solution is obtained. Now,
to prepare the polymer nanocomposite, firstly, the nanoparticle is added in a solvent,
and ultrasonication is performed for better dispersion. Then the obtained solution is
added to the polymer–salt solution and stirred till a homogenous solution is obtained.
Finally, the viscous solution is casted in the petri dish and kept at room temperature
for evaporation of the solvent and then kept in a vacuum oven to completely remove
the residual solvent, and film is peeled off from petri dish (Arya and Sharma 2018).
The obtained film is kept in a desiccator with silica gel for further characterization
and moisture prevention. For high-quality film, the solvent must be free from water
content and should dissolve the polymer, salt, and nanoparticle (Karuppasamy et al.
2015).
Spin Coating
This method is almost identical to the solution cast technique. The key advantages of
spin coating technique are simplicity and relative ease of preparation and produce
uniform films from a few nanometers to a few microns in thickness. In this
technique, a small amount of solution is dropped on a substrate and kept on the
spin coater which can be rotated at desired speed. The centripetal acceleration
spreads the mixture on a substrate followed by heating to evaporate the solvent.
One point that must be taken care of is that the substrate spinning axis must be
perpendicular to the substrate which is to be coated. The thickness of the film is
influenced by (i) viscosity of mixture, (ii) concentration of mixture, (iii) speed of
rotation, and (iv) spin time. However, this method is advantageous only for low
viscosity mixture not for too high viscosity mixture. For a gel mixture, the spin
coater rotation is not enough to spread the mixture droplet to form thin film (Park
et al. 2006; Krebs 2009).
274
A. Arya and A. L. Sharma