Pyridine modified acidic copolymers as a non covalent pi-interactions compatibilizers for carbon nanotube composites

Conductive polymer composites based on carbon nanotubes are attractive for the fabrication of antistatic plastics, electro-magnetic shielding materials, and conductive polymer substrates. The performances of those composites are very much dependent upon the ability to form a percolated network of carbon nanotubes throughout the polymer matrix. For the purpose of forming that network at relatively low nanotube loadings, an efficient dispersion of the nanotubes must be obtained. The dispersion of the nanotubes is controlled by many factors, in which the interactions between the nanotubes and the polymer matrix are the most important one.;In this research a new concept is demonstrated in which acidic copolymers have been modified with aminopyridine using a simple acid-base reaction, to form a compatibilizer that interacts with the carbon nanotubes via π-π interactions. The compatibilizer itself can be compatible with different types of polymers depending on the co-monomer type.;Even though the concept of π-interactions with carbon nanotubes is well established in the literature, this research diverged from the common approach of using special conjugated polymers (usually by solvent mixing techniques), and instead demonstrated the use acidic copolymers, which can be readily modified with aminopyridine, to produce a new class of effective carbon nanotube compatibilizers tailored to any specific polymer matrix in the range of commodity plastics to engineering polymers.;This multi-monograph dissertation starts with an introduction to the carbon nanotube electronic structure and their ability to form π-interactions with various types of molecules and polymers. This section introduces the theoretical background of non-covalent interactions with carbon nanotubes. The first monograph of the thesis experimental study demonstrates how poly(ethylene-co-methacrylic acid) can be modified with aminopyridine and used as a compatibilizer in poly(ethylene-co-methacrylic acid)/carbon nanotube composites to reduce the percolation threshold from 1.8 wt. % to 1.4 wt. %. Subsequently, the second monograph demonstrates the ability of the same pyridine modified copolymer to be used as a nanotube confining phase in a ternary polymer blend composite to form a unique hierarchical structure, where the nanotubes form a percolated network along the blend interfaces. In the third monograph, the concept is investigated in poly(methyl methacrylate) systems, where a low percolation threshold of less than 0.1 wt.% was achieved by introducing pyridine modified poly(methyl methacrylate-co-methacrylic acid). Finally, in the fourth monograph, the concept was applied to polyethylene systems, which were the most challenging, due to the low miscibility of the acidic copolymer with the hydrophobic polyethylene. Throughout this study, the electrical percolation phenomenon was used as the main indication of the nanotubes state of dispersion. All of the composites in the different experimental monographs were mixed by a simple melt extrusion processes.;A short summary present the importance and significance of the concept for future scientific research and also set forth toward some key elements needed to be examined prior to application of this generic technology.