![]() ![]() Journal reference: Science Advances, DOI: 10.1126/sciadv. “No new chemistries, materials or equipment are involved, so it’s ready for anyone to start using immediately.” Three-dimensional (3D) and Four-dimensional (4D) printing emerged as the next generation of fabrication techniques, spanning across various research areas, such as engineering, chemistry, biology, computer science, and materials science. Moreover, the technology could easily be used by people with other ideas, says Spinks. And flat-pack furniture could assemble itself when heated. By fine-tuning the temperature transition point, medicine capsules could also be designed to bend and break open when body temperature rises with infection. “This rules out applications that require reversible shape changes, like artificial muscles for robots and prosthetics,” he says.īut the method could be used to make complex structures that don’t require such shape-shifting, says Spinks.įor example, compact cardiac stents – tubes for placing in blood vessels to keep them open – could open up in an artery in response to body temperature. One limitation to the technique is that it permanently fixes the structure in place after one heating cycle, says Geoff Spinks at the University of Wollongong in Australia. As the strip cools, the shape-memory polymer stiffens again and locks the object into its new, curved configuration. When heated to 45☌, the shape-memory polymer component relaxes and allows the elastomer to bend. Lastly, perspectives and potential challenges facing 4D printing of LCEs are discussed.The strips, which can be printed in less than a minute, are made from layers of a stiff shape-memory polymer paired with a rubbery elastomer – a polymer with elastic properties. Within this scope, we elucidate the relationships among external stimuli, tailorable morphologies in mesophases of liquid crystals, and programmable topological configurations of printed parts. Unlike 3D printing, 4D printing allows the printed part to change its shape and function with time in response to change in external conditions such as temperature, light, electricity, and water. The past 5 years have witnessed rapid advances in both 4D printing processes and materials. Promising potentials of printed complexes include fields of soft robotics, optics, and biomedical devices. 4D printing has attracted great interest since the concept was introduced in 2012. In this review, we collect recent advances in 4D printing of LCEs, with emphases on synthesis and processing methods that enable microscopic changes in the molecular orientation and hence macroscopic changes in the properties of end-use objects. By patterning order to structures, LCEs demonstrate reversible high-speed and large-scale actuations in response to external stimuli, allowing for close integration with 4D printing and architectures of digital devices, which is scarcely observed in homogeneous soft polymer networks. ![]() Actuators are used as a controlling factor with multi-stage shape recovery, with emerging opportunities to customize the mechanical properties of bio-inspired structures. Owing to diverse polymeric forms and self-alignment molecular behaviors, LCEs have fascinated state-of-the-art efforts in various disciplines other than the traditional low-molar-mass display market. Four-dimensional (4D) printing is an advanced form of three-dimensional (3D) printing with controllable and programmable shape transformation over time. Liquid crystalline elastomers (LCEs) are polymer networks exhibiting anisotropic liquid crystallinity while maintaining elastomeric properties.
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