Nanocomposites dispersion problem

The dispersion problem in the case of polymer-polymer nanocomposites... 

In order to overcome these problems, hybridization of both materials (C and Si) in one electrode material by HTC seemed to be a promising option [75]. For this purpose, pre-formed silicon nanoparticles were dispersed into a dilute solution of glucose followed by hydrothermal treatment at 180 °C. The carbon-coated particles were then further treated at 750 °C in order to improve the conductivity and structural order of the carbon layer. It was shown that the hydrothermal treatment, following by high temperature carbonization, resulted in formation of a few nanometer thin layer of SiOx layer on the Si nanoparticles, effectively leading to a Si/SiOx/C nanocomposite. Some TEM micrographs of these materials are shown in Fig. 7.8. 

Because of the unique combination of mechanical, electrical, and thermal properties, the CNTs have been excellent candidates to substitute or complement the conventional nanofillers in the fabrication of multifunctional PNs. The first PNs using CNTs as the nanoadditive was reported in 1994.20 By far, the CNTs have been the second most investigated nanoadditives to reduce the flammability of the polymers through nanocomposite technology. A difficulty of the application of the CNTs in polymers is the dispersion of CNTs in the matrix polymer, and the high cost of the CNTs is another problem. 

Over the past decade, SCFT was often applied to analyze the problem of particle dispersion in polymers (thermodynamics of nanocomposites). Vaia and Giannelis (1997a, 1997b) formulated a simple version of SCFT... 

However, the simple melt mixing of polyolefins with natural clays, does not guarantee a sufficient level of dispersion of the nanoparticles, which are often present in the form of micron-size agglomerates. In order to overcome this problem, two main strategies have been followed surface functionalization of needle-like clays (usually by alkyl-silanes) or addition of a third polymeric phase (usually maleic anhydrite modified PP PP-g-MA), which acts as a compatibilizer between the matrix and nanofiller. Both methods tend to modify the surface energies of the nanocomposite system, in order to reduce the interparticle interaction and improve the dispersion. In the case of a reactive surface treatment only, the polymer-day interaction is expected to be enhanced, along with better nanoclay dispersion, which is very important for the final mechanical properties. 

---