SWCNT/PMMA nanocomposite

Figure 7.3. Optical micrographs of SWCNT-PMMA nanocomposite having 1 wt% purified soot (a) as-cast film (b) after 1 cycle (c) after 5 cycles (d) after 20 cycles. Reprinted with permission from Elsevier (21).

Recently, the thermal and mechanical properties of MWCNT/PMMA or SWCNT/PMMA nanocomposites have been thoroughly investigated [145, 146]. For instance, Lee et al. [146] reported the fabrication and characterization of MWCNT/PMMA by using both injection molding and film-casting processes. The tensile strength of the MWCNT/PMMA nanocomposite increased by more than 15% and tensile stiffness also increased by about 17.5%, compared to pure PMMA. It was confirmed that a combined fabrication process efficiently dispersed MWCNTs in the PMMA matrix and also maintained the well-dispersed state more effectively [146]. 

Benoit et al. (41) obtained electrically conductive nanocomposites by dispersing SWCNT and PMMA in toluene, followed by drop casting the mixture on substrates. Thin films of SWCNT-PMMA composites for different CNT concentration were produced by spin casting by Chapelle et al. (54) and Stephan et al. (55). They characterized these nanocomposites by Raman spectroscopy to study interactions between nanotubes and PMMA and found that PMMA tends to intercalate between the CNTs thereby increasing the distance between the nanotubes in the film. 

The impact of aspect ratio and alignment of the carbon nanotubes on the nanocomposite conductivity has been studied recently (both experimentally and computationally) by Winey and coworkers [165-167]. In particular, Du et td. [165] demonstrated that in a poly(methyl methacrylate) (PMMA)/single wall carbon nanotube (SWCNT) nanocomposite, conductivity increases as a function of the SWCNT loading as predicted by Eq. (7.10), with a power-law exponent of 2.3 and percolation threshold of 0.39 wt%. Interestingly, the rapid increase in conductivity was accompanied by a rapid increase in the storage modulus, G (Figure 7.17). In fact,... 

Figure 7.17 Storage modulus (a) and electrical conductivity (b) of poly(methyl methacrylate) (PMMA)/SWCNT nanocomposites. Insets power-law percolation model fits to experimental data. (Reprinted from Reference [165]).

---