Storing Light Energy As Mechanical Energy In Contractile Gel
A polymer gel that is able to contract when exposed to light — thereby storing mechanical energy through the actions of artificial molecular motors — has been developed by researchers at CNRS’s Institut Charles Sadron.
The effect is caused via the nanoscale motors, when exposed to light, twisting the polymer chains in the gel — thereby causing the material to contract somewhat.
Here’s a bit of background on the subject/mechanisms: in biological systems, molecular motors are very complex protein assemblies that can produce “work” via the consumption of energy. A great many things rely on them — everything from “movement,” to protein synthesis, to DNA copying. While individual molecular motors operate on the scale of nanometers (or less), when they coordinate together in collective actions numbering in the millions or billions, then macro-scale effects occur.
It’s, unsurprisingly, long been a goal of researchers in the field to produce similar motors — and motion of this type — artificially.
Here’s the technical information, via the study:
To achieve this, the researchers at Institut Charles Sadron replaced a gel’s reticulation points, which cross-link the polymer chains to each other, by rotating molecular motors made up of two parts that can turn relative to each other when provided with energy. For the first time, they succeeded in getting the motors to work in a coordinated and continuous manner, right up to the macroscale: as soon as the motors are activated by light they twist the polymer chains in the gel, which makes it contract.
Just as in living systems, the motors consume energy in order to produce continuous motion. However, this light energy is not totally dissipated: it is turned into mechanical energy through the twisting of the polymer chains, and stored in the gel. If the material is exposed to light for a long time, the amount of energy contained in the contraction of the polymer chains becomes very high, and can even trigger a sudden rupture of the gel. The researchers at Institut Charles Sadron are therefore now attempting to take advantage of this new way of storing light energy, and reuse it in a controlled manner.
It’s hard to say what exactly this technology can or will be used for as far as renewable energy goes, but it is interesting — something a bit different, and potentially useful in some ways, even if maybe only in niche applications.
The new research is detailed in a paper published in the journal Nature Nanotechnology.
Image Credit: Gad Fuks/Nicolas Giuseppone/Mathieu Lejeune
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The Institut Charles Sadron is associated with Strasbourg University. Jean-Marie Lehn, a professor there, got the Nobel Prize in Chemistry in 1987 for pioneering work in supramolecular chemistry (link), which seems to be related to the report. Light-powered artificial muscles? Somebody will think of a use. Self-steering solar trackers, say.
Or day to night power generation without batteries? This made me think about the gravity powered lights being distributed in communities without electricity where very little motive force is required but the pendulums need to be reset frequently. Perhaps a molecular spring that could gather force through the day could keep a porch or street light lit through the night without batteries.
This reminds me of some fingernail polishes that change color when exposed to sunlight. We were told that without sunlight there were minuscule dye “springs” that when contracted did not have enough surface area exposed to alter the color of the polish. When exposed to sunlight the “springs” unwound and presented enough surface area to change the color.