Plastic Withstands 1000℃ Flames...Polymers Challenge the Domain of Metals [Reading Science]

"Nanocages" Poised to Upend the High-Temperature Structural Materials Landscape for Aircraft-Grade Engines

A domestic research team has experimentally demonstrated that plastic composites can maintain structural stability even in 1000℃ flames and in high-temperature environments comparable to aircraft engines. This was achieved through a structural design that traps polymer chains in a three-dimensional "nano prison."

Polymer composites, which have been excluded from high-temperature structural components due to their vulnerability to heat despite being lightweight, are now presenting the possibility of replacing metals in extreme-environment materials markets such as aircraft engines and gas turbines.

The National Research Foundation of Korea announced that a research team led by Dr. Oh Youngseok at the Korea Institute of Materials Science designed and fabricated a three-dimensional carbon nanotube (CNT)-based "nanocage" structure and implemented it inside a polymer composite, successfully suppressing molecular motion effectively even at high temperatures. The team proposed a new approach that controls the thermal behavior of polymer chains not by changing the chemical composition, but by using a nanoscale physical confinement structure.

Thermal limits of polymer composites and the concept of physical confinement using carbon nanotube nanocages. Polymers undergo structural deformation above the glass transition temperature (Tg) due to free thermal motion of their chains (left). This study physically confines polymer chains within a three-dimensional carbon nanotube nanocage structure, securing thermal stability even at high temperatures (right). Bottom: an ultralight carbon nanotube aerogel-based nanocage specimen. Provided by the research team.

Limits of composites that collapse under high temperatures

Polymer composites have attracted attention as next-generation structural materials in the aerospace and energy sectors thanks to their light weight and excellent processability. However, they have had the limitation that once the temperature exceeds the glass transition temperature (Tg), the mobility of molecular chains increases sharply, causing a loss of mechanical performance and dimensional stability.

For this reason, in areas such as aircraft engines and gas turbines where high temperatures and loads act simultaneously, metallic materials such as titanium alloys have continued to dominate.

To overcome these limitations, efforts have been made to develop heat-resistant polymers, increase crosslinking density, and introduce nanofillers such as graphene, silica, and carbon nanotubes. However, there have been inherent limits to significantly raising the glass transition temperature beyond a certain level or fundamentally suppressing the free motion of polymer chains in the temperature range above Tg.

In particular, the problem has been repeatedly pointed out that due to non-uniform dispersion of fillers, the nanoconfinement effect does not translate into actual structural stability.

Chains confined in a "nano prison" stayed immobile even at high temperatures

The research team identified the core issue as "polymer chains that move freely above Tg" and chose a strategy to block this through structural design. They individually dispersed single-walled carbon nanotubes, entangled them into a three-dimensional network-like nanocage, and then infiltrated polymer resin into the interior of this nanocage.

When the pore size of the nanocage was controlled to be smaller than the cooperative rearranging region of the polymer chains, experiments confirmed that the thermal motion of the chains was extremely suppressed.

As a result, the glass transition temperature of the nanocage-based polymer composite increased to up to 350℃, an improvement of about 119% compared with conventional epoxy resin. This is close to the thermal decomposition temperature of the polymer itself. The composite stably maintained its elastic modulus even at temperatures above 300℃, and its coefficient of thermal expansion decreased to around 10 ppm/℃, exhibiting excellent dimensional stability.

In high-temperature creep tests, the strain remained below 1% in the 200–300℃ range, and in a flame exposure test at approximately 1000℃, the heat release rate decreased by about 98%, thereby simultaneously achieving fire-resistant and flame-retardant performance.

The research team further combined this nanocage-based composite with carbon fiber fabric to develop a micro–nano multiscale hybrid composite. As a result, it retained more than 90% of its initial elastic modulus even in a 370℃ environment, demonstrating superior high-temperature structural stability compared with commercial titanium alloys, which show performance degradation under the same conditions. This overturns the conventional belief that "lightweight design and heat resistance are difficult to achieve simultaneously" in high-temperature structural components.

This study dramatically extends the usable temperature range of polymer composites and suggests their applicability as components for next-generation aircraft engines and gas turbines.

In particular, due to their significantly lower weight compared with metals, these materials are expected to improve fuel efficiency and performance through engine weight reduction. They also show strong potential for use as safety materials that delay fire spread, not only in structures for supersonic vehicles and aerospace structures exposed to high-temperature thermal shocks, but also in electric vehicle battery packs.

Dr. Oh Youngseok said, "We plan to further increase the glass transition temperature to around 500℃ by forming composites with heat-resistant resins such as polyimide, and to verify long-term reliability and process stability under actual component conditions when combined with carbon fibers," adding, "We will secure process scalability and economic feasibility for manufacturing large components and move toward practical application."

Supported by the Nano Material Technology Development Program of the Ministry of Science and ICT and the National Research Foundation of Korea, the results of this study were published online on January 10, 2026, in the international journal on composites, Advanced Composites and Hybrid Materials.

This content was produced with the assistance of AI translation services.