Chinese researchers claim to have developed an advanced material that changes color depending on the light around itsimilar to how a chameleon does. Scientists have applied a process called Self-Adaptive Photochromism (SAP, for its acronym in English) that makes the color change occurs at the molecular level.
This advance has been carried out by a team led by Wang Dongshengof the University of Electronic Science and Technology China. ‘In other words, applying this technology to clothing could make that an individual is effectively “invisible”‘ Dongsheng told China Science Daily.
Current active camouflage systems have several limitations. According to the study published by the researchers, these usually include electronic components, which gives rise to complex structures, low usability and high costs. ‘In this work, we report on active camouflage as an intrinsic function of materials through the proposal of self-adaptive photochromism (SAP)’, they point out.
Color change at the molecular level
The new SAP materials are simpler, easier to use and less expensive. The key to SAP lies in the molecular structure. When these materials are exposed to specific wavelengths of light, the molecules rearrange, causing the material to change color..
Regarding their composition, the new materials use a combination of donor-acceptor Stenhouse adducts (DASAs) and organic dyes to achieve color changing properties. DASAs are a class of chemical compounds that possess unique color changing properties and whose behavior is based on specific electronic interactions between the donor and acceptor parts within their molecules.
‘SAP materials are in a primary black state in the dark and spontaneously change to another color when activated by transmitted and reflected light from the background,’ the study states.
Two experiments with SAP materials
According to the South China Morning Post, researchers conducted two experiments to demonstrate the capabilities of SAP materials.
In the first, a transparent container with SAP solution was placed in colored acrylic boxes (red, green, yellow and black). The SAP solution changed color to match the color of the surrounding acrylic box.
In the second experiment, the container with SAP solution was placed in environments with matching colors (groups of red, green or yellow plants). The solution adapted its color to integrate perfectly with the environment in a period of 30 to 80 seconds.
Use of smart coatings for military camouflage, architecture and fashion
Researchers have expanded the application of SAP technology to coatings. For this, they combined SAP materials with polycaprolactone (PCL) to create flexible films and coatings that can be applied to different surfaces.
This could make even solid surfaces are capable of adaptive camouflage. ‘SAP films and coatings were manufactured incorporating polycaprolactone and are applicable to a wide variety of surfaces‘, says the study.
In addition to smart coatingsSAP materials have potential in military camouflage, architecture and fashion. These materials can operate accurately in a temperature range ranging from from -20°C to 70°C.
The researchers plan to further develop SAP materials for expand your color range. Current materials can imitate various colors, but do not yet cover the entire visible spectrum, particularly purple and blue colors.