Nanoscale control of polymer crystallization by nanoimprint lithography

Polymer crystallization is notoriously difficult to control. Here, we demonstrate that the orientation of polymer crystals can be fully controlled at the nanoscale by using nanoimprint lithography (NIL) with molds bearing nanotrenches to shape thin films of poly(vinylidene fluoride). This unprecedented control is due to the thermomechanical history experienced by the polymer during embossing, to the shift of the nucleation mechanism from heterogeneous to homogeneous in confined regions of the mold, and to the constraining of the fast growth axis along the direction of the trenches. NIL thus appears as an ideal tool to realize smart polymer surfaces where crystal ordering can be tuned locally.