Structure and Energetics of Dislocations at Micro- Structured Complementary Interfaces Govern Adhesion

Highly enhanced adhesion can be achieved between surfaces patterned with complementary micro-channel structures. An elastic material, poly(dimethylsiloxane) (PDMS), is used to fabricate such surfaces by molding into a silicon master with micro-channel profi les patterned by photolithography. For each pair of complementary surfaces, dislocation defects are observed in the form of visible striations, where ridges fail to fully insert into the channels, and the rotational misalignment angle was found to be the key factor controlling the dislocation distribution and adhesion strength. Adhesion between complementary interfaces, as measured by energy release rate required to propagate an interfacial crack, can be enhanced by up to 30 times compared to a fl at control depending on the misalignment angle. The ability to control the orientation and periodicity of dislocation patterns by changing misalignment angle makes this system eminently controllable. This system could be a useful experimental tool in assisting research on geometry controlled adhesion, while providing a test-bed for stability theories of interacting dislocations and crack fronts.