Characterization of the nanoscale structure of polymeric materials is a major emphasis of the group. The tools we rely on include atomic force microscopy (AFM), transmission electron microscopy (TEM), scanning electron microscopy (SEM), small angle x-ray scattering (SAXS), small-angle neutron scattering (SANS), and rheology. In addition to being able to implement these tools, processing plays a prominent role in determining the final structure of the polymers under investigation.
The images below give an example of how nanoscale structure can change with processing conditions. The polymer under study is a rod-rod all-conjugated polymer, and one polymer block has significant crystallinity. As cast, the film structure is amorphous and featureless, but after extended solvent annealing in dichlorobenzene a periodic nanoscale structure emerges. In this example, the nanoscale structure is due to crystallization of poly(3-hexylthiophene) which can form crystalline ‘nanowires’ with well-defined diameters.
