#shape memory effect

New copper alloy shows shape memory effect at -200°C for space use

Researchers have developed a novel copper-based alloy that exhibits a special shape memory effect at temperatures as low as -200°C. The work has been published in the journal Communications Engineering. Shape memory alloys can be deformed into different shapes when cold, but will revert back to their original shape when heated (as if "remembering" their default state, like memory foam). This exciting new alloy has the potential to be used for space equipment and hydrogen-related technologies, where challenging, cold environments below -100°C are the norm. Previously studied shape memory alloys using Ni-Ti could not maintain their shape memory ability below -20°C, despite their otherwise practical characteristics.

Shape memory polymers with nanotips help solve micro-LED chip transfer problem

A research team at Pohang University of Science and Technology (POSTECH), has developed a novel dry adhesive technology that allows everything from microscale electronic components to common household materials to be easily attached and detached. The study was recently published in the journal Nature Communications, and the team was led by Professor Seok Kim in collaboration with Professor Kihun Kim (POSTECH), Professor Namjoong Kim (Gachon University), Professor Haneol Lee (Chonbuk National University), and Dr. Chang-Hee Son (University of Connecticut, U.S.).

Plastic-based spectrometers offer low-cost, compact solution for broadband spectral imaging

A multinational research team, including engineers from the University of Cambridge and Zhejiang University, has developed a breakthrough in miniaturized spectrometer technology that could dramatically expand the accessibility and functionality of spectral imaging in everyday devices. The study, titled "Stress-engineered ultra-broadband spectrometer," published in the journal Science Advances, describes a novel, low-cost spectrometer platform built from programmable plastic materials rather than conventional glass. These innovative devices operate across the full visible and short-wave infrared (SWIR) range—spanning 400 to 1,600 nanometers—which opens up a wealth of possibilities for real-world applications.

Polyurethane with shape memory change from foil to foam when heated

Researchers at the Fraunhofer Institute for Applied Polymer Research IAP have developed a foil that changes into polyurethane foam (PU foam) when heated—entirely without health risks. The foil allows for isocyanate-free foaming, thus improving workplace safety. Additionally, it offers logistics advantages for storage and transportation. The material can be customized for various applications ranging from the automotive and construction industries to packaging. The research is published in the journal Macromolecular Rapid Communications. "A frequently discussed aspect in the production of PU foam is the health risk at work from isocyanates, one of the main components in the chemical reaction that forms polyurethane," explains Dr. Thorsten Pretsch, head of the Synthesis and Polymer Technology research division at Fraunhofer IAP in the Potsdam Science Park.

In a collaborative effort between Texas A&M University and Sandia National Laboratories, researchers have significantly improved a new joining technology, interlocking metasurfaces (ILMs), designed to increase the strength and stability of a structure in comparison to traditional techniques like bolts and adhesives, using shape memory alloys (SMAs). ILMs offer the potential to transform mechanical joint design in manufacturing for aerospace, robotics and biomedical devices. "ILMs are poised to redefine joining technologies across a range of applications, much like Velcro did decades ago," said Dr. Ibrahim Karaman, professor and head of the Department of Materials Science and Engineering Department at Texas A&M. "In collaboration with Sandia National Laboratories, the original developers of ILMs, we have engineered and fabricated ILMs from shape memory alloys. Our research demonstrates that these ILMs can be selectively disengaged and re-engaged on demand while maintaining consistent joint strength and structural integrity."

Scientists probe chilling behavior of promising solid-state cooling material

A research team led by the Department of Energy's Oak Ridge National Laboratory has bridged a knowledge gap in atomic-scale heat motion. This new understanding holds promise for enhancing materials to advance an emerging technology called solid-state cooling. The findings are published in the journal Science Advances. An environmentally friendly innovation, solid-state cooling could efficiently chill many things in daily life, from food to vehicles to electronics—without traditional refrigerant liquids and gases or moving parts. The system would operate via a quiet, compact and lightweight system that allows precise temperature control. Although the discovery of improved materials and the invention of higher-quality devices are already helping to promote the growth of the new cooling method, a deeper understanding of material enhancements is essential. The research team used a suite of neutron-scattering instruments to examine at the atomic scale a material that scientists consider to be an optimal candidate for use in solid-state cooling.

Moisture-resistant hairstyling agent: Development of a humidity-induced shape memory polymeric material

NIMS and Nihon L'Oréal K.K. have developed a shape memory polymeric material responsive to humidity. This innovative material, when applied to a person's hair and allowed to dry, serves as an exceptionally moisture-resistant hairstyling agent. The research was published in Advanced Materials Interfaces. Hairstyles play a crucial role in personalizing one's appearance and showing self-confidence. Demand for effective and functional hairstyling products has been growing. Weather-related humidity and sweat from exertion have long been a problem for hairstyle stability. Most currently available hairstyling products (e.g., hair sprays and gels) merely create a physical barrier on the hair's surface, offering limited protection against humidity. There is a considerable expectation for the development of advanced, highly moisture-resistant hairstyling agents. This research team recently developed a humidity-responsive shape memory polymeric composite designed as a moisture-resistant hairstyling agent. The material's moisture resistance stems from the hydrogen bonding between polyvinyl alcohol (PVA) and naturally occurring cellulose microcrystals (CMs), forming a robust PVA/CM network.

Novel durable copper-aluminum-zinc shape memory alloys for energy-efficient refrigeration

The elastocaloric effect is a phenomenon where a material displays a temperature change when it is exposed to a mechanical stress. The change in temperature occurs due to an entropy difference resulting from a martensitic transformation accompanied by material's crystal structure change under stress.

An analogous effect is observed when the rubber band is stretched: its polymer chains line up in an ordered manner, causing its entropy to decrease. This leads to the rubber band discharging heat to its surroundings and becoming warmer. When the rubber band is released, the opposite occurs, and the rubber band cools down.

Like rubber bands, metallic superelastic shape memory alloys (SMAs) can also utilize the elastocaloric effect for cooling. Copper (Cu)-based SMAs consisting of Cu, aluminum (Al), and zinc (Zn) are particularly promising due to their low cost and modest stress demands for triggering the temperature lift. However, Cu-Al-Zn SMAs suffer from cyclical fatigue issues as their coarse crystal grains and numerous grain boundaries are susceptible to fracture from repeated expansion and contraction.