Stretching usually makes a conductive material harder to rely on: particles can move apart and interrupt pathways. A 2026 study reports the opposite thermal response in a specially engineered composite of silver nanosatellites and silicone rubber. As strain widens the nanoscale barriers between particles, the material’s thermal conductivity rises, while its thermal conductance stays nearly unchanged. The university announcement also says electrical conductivity increases with stretching, though it does not provide numerical electrical-conductivity results.
What material did the researchers make?
The study, “Ballistic-Like Thermal Transport Between Fillers in Highly Conductive Stretchable Nanocomposites,” by C. Muhammed Ajmal and colleagues, was published online by Advanced Functional Materials on August 24, 2026. The researchers describe a silicone-rubber composite containing silver nanosatellite particles generated in situ. The journal abstract reports particles measuring 3.4 nm and a barrier width of 4.1 nm. Read the paper record at Wiley.
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This is a result for a particular engineered material and spacing regime, not evidence that stretching ordinary rubber, silver-filled composites, or conductive materials generally improves heat or electricity flow.
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Why can stretching increase thermal conductivity?
In a typical material, heat moves through phonons—vibrations that carry energy through the material. In this composite, the authors focus on the nanoscale barrier between neighboring silver particles. Stretching lengthens the channel across that barrier. The paper reports that thermal conductivity, κ, increases as this channel length or barrier width increases, even though the thermal conductance remains strain-invariant.
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The abstract reports a phonon mean free path of 9.3 nm, longer than the initial 4.1 nm barrier width. The authors connect the unusual response to the barrier’s dimensions and properties: when the gap is very short relative to the reported mean free path, transport between fillers can behave in a “ballistic-like” way. That term describes transport between particles; it does not mean heat travels through the entire bulk composite without scattering.
The paper reports thermal conductivity of 21.94 W m−1 K−1 for the composite. That is a study-specific figure, not a benchmark for stretchable composites as a class. The abstract also describes diffusive transport at barrier widths of at least 1.3 µm regardless of barrier height, and a tunneling-dominated regime below 5 nm when barrier height is non-negligible. These are the paper’s descriptions of its transport regimes, not universal cutoffs for other materials.
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What does the study say about electrical conductivity?
Sungkyunkwan University’s announcement says electrical conductivity also rises as the material is stretched. The journal abstract information available here does not give a numerical electrical-conductivity value or its measurement conditions, so the electrical result should be treated as an announcement-level claim rather than a quantified performance specification. Read Sungkyunkwan University’s announcement.
The university says simulations showed polymer chains aligning with the direction of strain, enabling more efficient heat transfer. That account offers a complementary explanation of how deformation may affect transport in the rubber matrix; it does not establish that the same response will occur in unrelated composites.
Could this help cool flexible electronics?
The researchers identify heat management in flexible electronics, including foldable phones, as a possible application. Professor Seunghyun Baik said the work “discovered a unique physical phenomenon where thermal conductivity increases upon stretching through the precise control of nanoscale energy barriers” and described successful application to heat management in flexible electronics. The available announcement does not quantify a phone-scale demonstration or establish device performance, durability, or commercial readiness.
The university also describes tuning particle spacing and rubber chemistry as a possible route to a thermal-switching material. That is a potential direction, not a demonstrated retail product. The sources identify no commercially available version of the engineered composite.
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What remains unknown from the published summary?
The journal abstract and university announcement establish the reported material, selected thermal figures, and proposed mechanism and application. They do not provide a complete basis for judging product readiness or comparing this material fairly with other composites.
Quick Recap
- The exact strain range and full conductivity-versus-strain data are not stated in the available summary.
- Numerical electrical-conductivity measurements and their test conditions are not stated in the university announcement.
- Cyclic durability, long-term stability, and detailed device-level performance are not established in these sources.
- A like-for-like comparison with other materials would require measurements under comparable conditions, including strain range, conductivity, barrier geometry, and cycling.
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