Page 235 - Polymer-based Nanocomposites for Energy and Environmental Applications

Polymer nanocomposites for sensor devices 207

7.2.1 In situ reaction

In situ polymer techniques for preparation of nanocomposites mostly carry in the
presence of suitable initiator like heat and radiation. In this technique, the nanoparticle
gets intermixed with liquid monomer or in monomer solution.

7.2.2 Solution casting technique
Solution casting method is based on the principle of Stokes’ law. In this method,
polymer and prepolymer are equally merged and make soluble in the suitable solution.
The polymer being the matrix phase dissolved easily soluble in the solution, whereas
the nanoparticles dispersed in same solution or different solution. Finally, both got
intermixed. For example, during preparation of clay-based nanocomposites, the solu-
tion must be swell to clay that indicates the miscibility [15]. The clay is dispersed due
to weak van der Waals’ force such that layers are filled one over another in a multi-
layered fashion. The solution is dispersed on clay after the process of swelling; within
the solvent, there occurs lysis or breaking of long polymeric chain. The solvent
particles are adsorbed on to the silicate surface. There occurs a decrease in entropy
due to desorption of solvent molecules from polymer/clay composites. In this manner,
the entropy decreases to establish intercalated chain. Due to evaporation of solvent
molecules, nanocomposite structure is established [16].

7.2.3 Melt mixing technique

In melt-mixing technique, the nanoparticles mixed each other in the molten state.
In this process, the mixing of particle and modified clay proceeds to degradation.
The melted nanocomposite clay sustained long period is called peeling of platelets.
Certain nanocompound like CNTs dispersed the nanoparticles that means breakage
of nanoparticle. In melting process, the agglomeration nanoscale dispersed the
particle. The temperature and pressure depend on the degradation of polymer.

7.3 Brief description about synthesis of nanostructured
polymers for sensor devices

Nanostructured polymers in the last two decades have great importance in biological
and technology sector, especially in drug delivery, catalysis, photonics, and sensor
applications [17]. Few synthesis of nanostructure polymer are explained below.

7.3.1 Synthesis of nanostructure polymers for gas sensors
The synthesis of nanostructure polymers that are used for sensor applications is mainly
carried out by bottom-up synthesis pathway, i.e., it starts with monomer molecules to
the nanostructure. The schematic pathway for synthesis of such gas-sensing polymers
is given below (Fig. 7.1).