Nanocomposite film formation preparation

Figure 3.14. CNT/polymer nanocomposites observed in SEM (a) and (b) P(S-ABu)/MW CNT films surface respectively prepared by evaporation and film formation or freeze-drying and hot-pressing but showing similar fillers distribution (c) and (d) PS matrix containing ungrafted or PS-grafted N-doped CNT a fracture performed at ambient temperature highlights the difference in fillers/matrix interface strength. Scale bars 1 pm.

Ihe ECP/CNM nanocomposites can be prepared mainly in two ways (i) in-situ chemical oxidative polymerization, and (ii) in-situ electrochemical polymerization. In an in-situ chemical polymerization, CNM is added into the dispersion containing monomers and oxidant, and the reaction takes place over a period of time. Even a mixture of CNMs can also be used simultaneously. The monomers are polymerized on the surfaces of CNMs. In an in-situ electrochemical polymerization, CNMs are added into the dispersion containing monomer, and the polymerization takes place by the application of electric field for a short period of time, and the nanocomposite films are deposited onto the surface of substrate. Any electrically conducting substrate can be used, such as metal plates. The polarity of substrate and the charges present on the CNM should be accounted for the effective formation of nanocomposites. The thickness of ECP/CNM nanocomposite thin films deposited on the substrate can be controlled by varying the electric field and deposition time. 

The Cgg doped with neutral polymers such as emeraldine base of polyaniline show higher conductivities due to the charge transfer complex formation mechanism whereby the neutral polymer acts as electron donor and Cgg acts as acceptor [22]. Not only Cg, but also a combination of and can be doped with polyaniline, where the same effect of enhancement in conductivity is observed (of the order of 10 ). But, when doped polyaniline is prepared from N-methyl-2-pyrrolidinone (NMP)/toluene-solution, a slightly lower conductivity is observed. The free-standing nanocomposite films possess conductivities up to 6.2 x 10 S/cm [23]. 

Fortxmati et al. [56] studied PLA/nanocellulose nanocomposite films prepared by twin-screw extrusion followed by a film formation process. Cellulose nanocrystals were synthesized from cellulose microcrystals by sulphuric acid hydrolysis. The crystal surface was modified with surfactant (acid phosphate ester of ethoxylated nonylphenol) as a means to improve the dispersion of filler in PLA matrix. The presence of surfactant... 

Tian et al. [56] have studied poly(G-caprolactone)-silica and Sengupta et al. [57] have investigated nylon 66-silica hybrid systems and have observed that the phase separation started when Si/H20 mole ratio is increased above 2 and the resultant hybrid films become opaque. Gao [11] has reported similar observations on sol-gel-derived ionomeric polyethylene-silica system. A wide range of literatures is not available on this topic of mbber-silica hybrid nanocomposites, though Bandyopadhyay et al. [34,35] have reported the hybrid formation with different TEOS/H2O mole ratios from ACM and ENR and also demonstrated detailed structure-property correlation in these systems. The hybrids have been prepared with 1 1, 1 2, 1 4, 1 6, 1 8, and 1 10 TEOS/H2O mole ratios. Figure 3.14 shows the morphology of the ACM-silica hybrid composites prepared from different TEOS/H2O mole ratios. 

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