Pattern Imprinted Polyacrylonitrile Thin Films Using an Ionic Liquid

Polyacrylonitrile (PAN)-based conductive graphitic microstructures have tremendous potential for a variety of applications such as patterned electrodes, and anisotropic conductive films in the electronics industry due to its high carbonization yield. However, because of the crystallinity and high melting point of pristine PAN, thin films are difficult to get patterned at routine temperatures and pressures via methods such as capillary force lithography (CFL), a straightforward lithographic technique. We demonstrate that adding ionic liquid (IL) can greatly improve the imprintability of PAN by decelerating the crystallization rate and providing the needed mobility at accessible temperatures for efficient mold filling. The effect of IL additives concentration, annealing temperature and hold time of patterned PDMS elastomer on the imprintability of PAN are well-correlated in a balancing act. The resulting patterned films demonstrate extraordinary IL removal ability at the end of the process, and thermal stability of final patterned structures, promising results on easy patterning route to create graphitic structures after carbonization for multitude of applications ranging from sensors to membranes.