Bioinspired Microadhesives with Greatly Enhanced Reversible Adhesion Fabricated by Synthesized Silicone Elastomer with Increasing Phenyl Contents.

We present a facile chemical method for fabricating bioinspired microadhesives with significant improved reversible adhesion strength. Four kinds of polysiloxane with gradient varying phenyl contents were synthesized and used to fabricate microadhesives. The chemical structures and mechanical properties, as well as surface properties of the four microadhesives, were confirmed and characterized by ATR-FTIR, DSC, XPS, low-field NMR, tensile tests, and SEM, respectively. The macroadhesion test results revealed that phenyl contents showed remarkable and positive impacts on the macroadhesion performance of microadhesives. The pull-off adhesion strength of microadhesives with 90% phenyl content (0.851 N/cm) was nearly 300% higher than that of pure PDMS (0.309 N/cm). The macroadhesion mechanism analysis demonstrates that a larger bulk energy dissipation caused by massive π-π interaction, as well as the hydrophobic interaction and van der Waals forces at the interface synergistically resulted in a significant enhancement of the adhesion performance. Our results demonstrate the remarkable impact of chemical structures on the adhesion of microadhesives, and it is conducive to the further improvement of adhesion properties of bioinspired microadhesives.