Abstract
In this study we investigate the formation of non-covalent electron donor–acceptor (EDA) interactions
between polymers and single-walled carbon nanotubes (SWNTs) with the goal of optimizing interfacial
adhesion and homogeneity of nanocomposites without modifying the SWNT native surface.
Nanocomposites of SWNTs and three sets of polymer matrices with varying composition of electron
donating 2-(dimethylamino)ethyl methacrylate (DMAEMA) or electron accepting acrylonitrile (AN)
and cyanostyrene (CNSt) were prepared, quantitatively characterized by optical microscopy and
Raman spectroscopy (Raman mapping, Raman D* peak shifts) and qualitatively compared through
thick film composite visualization. The experimental data show that copolymers with 30 mol%
DMAEMA, 45 mol% AN, 23 mol% CNSt and polyacrylonitrile homopolymer have the highest extent
of intermolecular interaction, which translates to an optimum SWNT spatial dispersion among the
series. These results are found to correlate very well with the intermolecular interaction energies
obtained from quantum density functional theory calculations. Both experimental and computational
results also illustrate that chain connectivity is critical in controlling the accessibility of the functional
groups to form intermolecular interactions. This means that an adequate distance between interacting
functional groups on a polymer chain is needed in order to allow efficient intermolecular contact.
Thus, controlling the amount of electron donating or withdrawing moieties throughout the polymer
chain will direct the extent of EDA interaction, which enables tuning the SWNT dispersion.
