Mechanochromic is the new black

Clothing has always used color to convey cultural identity, societal functions, or social standing. But, for centuries, fabric colors were subject to exacting mineral extractions and tortuous supply chains that consigned humanity’s limited palette to a lucky few.

As a consequence, for much of our history, the evolution of color in clothing could be measured in eras. In fourth-century Byzantium, for example, the emperor forbade anyone outside of the imperial family from wearing purple, on pain of death. During the Middle Ages, royal folk favored deep crimson — the symbolic color of Christ’s blood and a reminder that the wealthy claimed a theory of divine right in God’s earthly realm.

Blue took on similar religious associations with Christ’s mother, Mary, during the 12th century and the color became a favorite among French royalty. Across the English Channel, purple enjoyed a brief royals-only revival under King Henry VIII.

Courtesy of iStock.com/Georgii Boronin.

Then, 300 years later, a British chemist named William Henry Perkin virtually democratized purple by accidentally synthesizing a purple dye while trying to find a treatment for malaria. By then, however, the age of fashion had taken root and the use of particular colors in clothing was as fleeting as the seasons.

Today, Pantone issues a color of the year for clothing designers wishing to stay au courant. Purple is in again for 2023, according to the color institute. Or, technically, the color is called Viva Magenta 18-750.

Given today’s fierce competition among French, German, and Italian designers to set trends for color, it’s improbable that clothing could update its shades any more quickly. And yet, a team of researchers from the University of Luxembourg might soon change the fabric of that reality.

In a paper recently published in Nature Materials and written by Yong Geng, Rijeesh Kizhakidathazhath, and Jan Lagerwall, the researchers describe the ability to draw fibers that change color based on mechanical forces, such as movement and stretching.

The fibers are composed of a cholesteric liquid crystal elastomer (CLCE), which has a predictable and reversible mechanochromic response that spans the visible spectrum over a broad elastic range, according to the paper. In other words, stretching the fibers shifts their color across a 145-nm range from blue to red.

Other textile technologies exist that are capable of changing color. But the Luxembourg researchers’ CLCE threads are notable because they can be produced at scale, and they appear to be both robust and flexible enough to be sewn into a comfortable fabric that can be tossed repeatedly into the wash.

The technology invites speculation about applications — from wearable robotics, to a smart rope that indicates when it is under dangerous strain. It is likely only a matter of time before the researchers’ technology ushers in a generation of “hyper-courant” fashionistas capable of creating new color ensembles simply by striking a pose.