  Bioinspired structure adhesives have received increasing interest for many
applications, such as climbing robots and medical devices. Inspired by the
closely packed keratin nanopillars on the toe pads of tree frogs, tightly
arranged polycaprolactone nanorod arrays are prepared by mold process and
chemical modification. Nanorod arrays show enhanced adhesion and friction on
both smooth and rough surfaces compared to the arrays with hexagonal
micropillars. The bonding of nanorods results in a larger stiffness of the
nanorod surface,contributing mainly to friction rather than adhesion. The
results suggest the function of closely packed keratin nanopillars on the toe
pad of tree frogs and offer a guiding principle for the designing of new
structured adhesives with strong attaching abilities.
