Methods to Disperse Individual CNTs in a Polymer Matrix

An alternative to acid-based chemical purifications is thermal annealing. This strategy has been reported to lead to the removal of most amorphous carbon impurities, as well as of residual catalyst particles. It has even been reported to increase the graphitic perfection of the CNTs. Formation of graphitic shells and other undesirable nanoparticles, however, may be promoted. Note that thermal annealing can also be used in combination with acid-based chemical treatments.  

5 Methods to Disperse Individual CNTs in a Polymer Matrix 

---

Several methods have been developed over the last few years to achieve an efficient dispersion of individual CNTs in a polymer matrix. The easiest method consists of directly mixing the polymer and the CNTs. One can also either modify the polymer in such a way that it can interact with the Ti-system of the CNT wall, or modify the walls of the CNTs by functionalization to improve the wetting of the filler, as well as the dispersion in the medium. It is also possible to use a third component, such as surfactant molecules, to assist the exfoliation of the CNT bundles, and the subsequent incorporation of the CNTs into the polymer matrix. All main methods reported so far are briefly discussed below, and are illustrated with representative examples. In this way, a guided tour through the tool-box for the dispersion of CNTs into highly viscous polymer matrixes is offered. 

Blau and co-workers prepared a CNT-polymer hybrid by suspended SWNTs in organic solvents poly (p-phenylenevinylene-co-2,5-dioctyloxy-m-phenylenevinylene) to wrap the copolymer around the CNTs. The electrical properties of these hybrids were improved relative to those of the individual components. A noncovalent method has been used to functionalize SWNTs by encapsulating SWNTs within cross-linked and amphiphilic poly(styrene)-blocfe-poly(actylic add) copolymer micelles (Figure 19). This encapsulation significantly enhanced the dispersion of SWNTs in a wide variety of polar and nonpolar solvents and polymer matrices because the copolymer shell was permanently fixed. Thus, encapsulated SWNTs may be stabilized with respect to typical polymer processing and recovery from the polymer matrix. 

---