Polymer nanotube nanocomposites: Correlating intermolecular interaction to ultimate properties

Polymer nanocomposite films containing 5 wt% single-walled carbon nanotubes (SWNT) or 5 wt% multi-walled carbon nanotubes (MWNT) with random copolymers of styrene and vinyl phenol were processed from dimethyl formamide solutions. Vinyl phenol mole ratio in the copolymer was 0, 10, 20, 30, and 40%. FTIR analysis indicates that the composites containing the copolymer with 20% vinyl phenol exhibit the maximum intermolecular interactions (hydrogen bonding) between the hydroxyl group of the vinyl phenol and the carbon nanotube functional groups. Tensile properties and electrical conductivity also are the highest in the samples containing the copolymer with 20% vinyl phenol. Thus, these results show that the optimization of the extent of intermolecular interactions between a polymer chain and a carbon nanotube results in an optimal increase in macroscopic properties. Moreover, the extent of intermolecular hydrogen bonding can be improved by optimizing the accessibility of the functional groups to participate in the non-covalent interaction. In this system, this optimization is realized by control of the amount of vinyl phenol in the copolymer, i.e. the copolymer composition.