BEER-SHEVA, Israel, January 5, 2026 – Chemists at Ben-Gurion University of the Negev have developed a "smart" polymer that could make industrial curing, 3D printing and repairs simpler, safer and more energy-efficient with materials whose properties may be tuned to match the required application.
Their findings were published last month in Nature Chemistry ( https://www.nature.com/articles/s41557-025-02011-7 ).
For nearly thirty years, researchers who tried to control when and where plastics harden focused on designing special "sleeping" catalysts, molecules that stay dormant until they are triggered by light, heat, or another signal. These catalysts are often sensitive, expensive, and difficult to handle.
The BGU team turned this logic on its head, as PhD student Nir Lemcoff, one of the lead authors on the paper, described, "This work demonstrates a new way of thinking about a general problem in polymer science and will hopefully inspire scientists in the field to look at the challenges in their own work with a fresh point of view".
Instead of trying to put the on/off switch in the catalyst, they hid it inside the plastic building blocks themselves, creating so-called "latent monomers." These are stable liquid building blocks that remain inactive for weeks. They then "snap" into a solid plastic-like material only when exposed to light or gentle heating.
These new latent monomers are built from small molecules called norbornadienes. Norbornadienes can be opened and linked into long chains by a standard plastic-making method called ROMP (ring-opening metathesis polymerization). When UV light is shined on them, they change into a different form called quadricyclane, which is basically the "off" state: it is inactive and does not build chains. Later, gentle heating with tiny gold nanoparticles switches quadricyclane back "on" to the reactive norbornadiene, so the chain-building can start again on demand. Because chemists can easily make many different norbornadienes, this switchable system could give rise to hundreds of new plastic-like materials, including some that are very hard to make with existing methods.
"Instead of a 'sleeping' catalyst, we created 'sleeping' building blocks of the material itself," explains Prof. Yossi Weizmann of the Department of Chemistry at Ben-Gurion University, who led the study. "The mixture can sit quietly on the shelf for weeks and will snap together into a solid only when you shine light on it or warm it up. That kind of on-demand, light-driven curing could make industrial production, printing, and repair processes safer, simpler and more energy-efficient."
The new liquids contain three key ingredients:
- Building blocks that can link together into long plastic-like chains
- A standard industrial catalyst that drives the chain-forming reaction
- Tiny gold nanoparticles that act as microscopic heaters when illuminated with near-infrared light
In their "sleeping" state, the latent monomers are locked in a form that does not react, even though the catalyst is already present. When the researchers shine light on the gold nanoparticles, they heat up their immediate surroundings and flip the monomers into an "active" form that quickly links into a solid material. The same switch can also be thrown by conventional heating, but not as efficiently.
Since nothing happens until the trigger is applied, manufacturers could in principle:
- Store and ship a ready-to-use liquid formulation for weeks without it thickening or hardening
- Fill, coat, or print parts first, and only then turn on curing in selected regions using light patterns or masks
- Reduce waste and energy use by avoiding the need to constantly mix fresh batches or heat entire volumes for long periods
The study also shows that this idea of switchable building blocks can do much more than simply turn a reaction on and off. By mixing building blocks that are active from the start with others that stay asleep until they are heated, the team can make plastics whose chains have two different sections, which gives materials with combined properties in one product. They can also first create a soft material that is easy to shape and later lock it into a tougher and more durable solid, all in a single process.
Prof. Weizmann is a member of the Zuckerman STEM Leadership Program.
Additional researchers on the project, all from Ben-Gurion University of the Negev, include Ronny Niv from Prof. N. Gabriel Lemcoff's group who are joint first authors on the paper, as well as Keren Iudanov from the Lemcoff lab, and Gil Gordon, Aritra Biswas, Uri Ben-Nun and Ofir Shelonchik from the Weizmann lab.
The work was supported by the Israel Science Foundation (ISF, grant no. 2491/20) and the United States–Israel Binational Science Foundation (BSF, grant no. 2020144).
