This lump of polymer may look nice and smooth right now, but given a shove it can form complex pasterns of ridges or bumps on its surface—the result of 3D printing the harder, black material within a softer matrix.

The material’s been created by a team from MIT using a 3D printing process to accurately place rigid polymer particles within much more flexible surroundings. When compressed, the differences in stiffness cause the surface to change shape, from smooth to something else altogether. Complex computer modelling enable the team to finely tune the resulting patterns, allowing them to create bumps, ridges and other complex structures on the surface. You can see what that looks like graphically in the image below.


The changing surface shape could be used to create materials that reflect light differently when they’re subjected to stresses, say, or perhaps change their aerodynamic properties to increase or decrease drag. The researchers also suggest that the changing shapes could be used to channel fluids in one direction or the other, or to create surfaces that are slippery in one direction and resistive to motion in the other. Now, the team is investigating how the materials could react in the same way to electric charge, or by changing temperature or humidity. [Advanced Functional Materials via PhysOrg]