Keywords: dry adhesion, geckos, gecko adhesion, poly(dimethylsiloxane), PDMS, ATRP, atom transfer radical polymerisation, polymer brushes, poly(butyl acrylate), biomimetic dry adhesives, nanotechnology, microstructure
Polymer brushes for improvement of dry adhesion in biomimetic dry adhesives
Geckos' feet are extensively micro–structured, enabling geckos to adhere strongly to most surfaces and perform various manoeuvres even while upside down. Inspired by the structure of geckos' feet, a large number of biomimetic dry adhesives have been reported. Polymers brushes can offer a molecular scale attachment to surfaces; here we studied the effect of polymer brushes on adhesion. Atom transfer radical polymerisation (ATRP) was used to graft poly(butyl acrylate) brushes on a poly(dimethylsiloxane) (PDMS) surface using a surface–bound ATRP initiator. Growth of the polymer brushes was verified by ATR–FTIR spectroscopy. To study the effect of polymer brushes, the samples were tested for pull–off adhesion with and without the grafted chains. The polymer–grafted PDMS showed an increase in adhesion compared to unmodified PDMS. Results suggest that carefully selected polymer brushes will enhance the adhesion of microstructured biomimetic adhesives.