A route to self-organized honeycomb microstructured polystyrene films and their chemical characterization by ToF-SIMS imaging

A new type of polymer compound that allows the formation of highly ordered microstructured films by casting from a volatile solvent in the presence of humidity, and its characterization by ToF-SIMS (time-of-flight secondary-ion mass spectrometry) are presented. A honeycomb structure is obtained by activation of 2,2,6,6-tetramethyl-1-piperidinyloxyl (TEMPO)-terminated polystyrene (PS) with p-toluenesulfonic acid (PTSA). The mechanism of this activation reaction, leading to a more polar PS termination, is deduced from simple experiments and supported by ToF-SIMS characterization. Positive and negative ToF-SIMS imaging allows different chemical regions correlating to the film morphology to be distinguished. This new, straightforward activation process, together with ToF-SIMS chemical imaging, provides a better understanding of the phenomena underlying the formation of these films by directly linking the role of polar terminations to the microscale self-organization. This new method, transposable to other organic acids, suggests interesting new perspectives in the field of self-organized chemical and topographical patterning