The capability of
fabricating multiscale structures with desired
morphology and incorporating them into engineering applications is
key to realizing technological breakthroughs by employing the benefits
from both microscale and nanoscale morphology simultaneously. Here,
we developed a facile patterning method to fabricate multiscale hierarchical
structures by a novel approach called creep-assisted sequential imprinting.
In this work, nanopatterning was first carried out by thermal imprint
lithography above the glass transition temperature (<i>T</i><sub>g</sub>) of a polymer film, and then followed by creep-assisted
imprinting with micropatterns based on the mechanical deformation
of the polymer film under the relatively long-term exposure to mechanical
stress at temperatures below the <i>T</i><sub>g</sub> of
the polymer. The fabricated multiscale arrays exhibited excellent
pattern uniformity over large areas. To demonstrate the usage of multiscale
architectures, we incorporated the multiscale Nafion films into polymer
electrolyte membrane fuel cell, and this device showed more than 10%
higher performance than the conventional one. The enhancement was
attributed to the decrease in mass transport resistance because of
unique cone-shape morphology by creep-recovery effects and the increase
in interfacial surface area between Nafion film and electrocatalyst
layer