The technology of double-sided 4D printing has been developed, which does not require the use of a hydrogel or human intervention to change the shape of an object.
Four-dimensional printing refers to the ability of 3D objects made with a 3D printer to reversibly change their shape in response to external factors such as heat or moisture. Previously, to return to the initial state, it was necessary to manually stretch or straighten the object, which could require significant effort and time.
In recent years, scientists have been able to achieve automatic shape change, but this effect is achieved through the use of a hydrogel as a stimulant. The problem is that it has insufficient mechanical strength, so it severely restricts the use of manufactured objects. Other options using alternative materials made the reversibility process very slow.
To address these of problems, researchers from the Singapore University of Technology and Design, together with colleagues from Nanyang Technological University, used only two materials (rigid VeroWhitePlus and rubber-like TangoBlackPlus), which are suitable for inkjet 3D printing and are able to maintain significant mechanical strength during and after activation.
During testing, the team impregnated the elastomer with ethanol, simulating the swelling process of the hydrogel, to stress the transition material, which changes shape with temperature. After the alcohol has evaporated, heating the transition material again restores its original shape, since the elastomer pulls it back due to the elastic deformation energy accumulated in it after drying..
Elastomer serves a dual function, inducing stress during the programming phase and storing energy in the material during reconditioning. At the same time, the process of returning to the initial state turned out to be more accurate compared to other alignment methods..
Although this approach is still in its infancy, its further development could provide a wide range of applications for the proliferation of 3D printing in the future.. It will allow you to create complex structures that can transform under the influence of the environment. For example, smart curtains that automatically respond to heat levels throughout the day without any sensors or electronics.
We also previously reported on the development of 4D printing systems for making plastic rods that can bend, fold and twist into desired shapes when exposed to heat.
text: Ilya Bauer, photo and video: YouTube / SUTD