Researchers at the University of Massachusetts Amherst with collaborators from Massachusetts Institute of Technology, North Carolina State University, Stanford University, Oak Ridge National Laboratory, Argonne National Laboratory and Rice University, have unveiled a counterintuitive strategy for boosting the thermal performance of polymer–filler composites. Deliberately introducing defects into graphite to form graphite oxide fillers. By harnessing oxygen-related functional groups at the filler–polymer interface, they achieve enhanced vibrational coupling and “thermal bridges” that outperform even pristine graphite in interfacial heat transfer. The research paper this interview pertains to, published in Science Advances, can be found here:
Zhou, Y., Ciarla, R., Boonkird, A., Raza, S., Nguyen, T., Zhou, J., Osti, N. C., Mamontov, E., Jiang, Z., Zuo, X., Ranasinghe, J., Hu, W., Scott, B., Chen, J., Hensley, D. K., Huang, S., Liu, J., Li, M., & Xu, Y. (2025). Defects vibrations engineering for enhancing interfacial thermal transport in polymer composites. Science Advances, 11(4). https://doi.org/10.1126/sciadv.adp6516
In our earlier coverage, we explored the conventional methods on interfacial thermal transport; denser polymer packing, shorter chain-to-filler distances, higher intrinsic filler conductivity, and smoother surfaces—and how these principles have long guided composite design.
Now, we sat down with Yanfei Xu, Assistant Professor, Mechanical and Industrial Engineering at the University of Massachusetts Amherst, one of the lead investigators to unpack the key mechanisms behind defective-filler-enabled heat transport, the modified Hummers synthesis and multimodal characterisation techniques they employed, the surprising extent to which defects can outdo crystalline graphite, and the path toward scalable, real-world applications in electronics cooling, biomedical thermal therapy, and beyond.
you can find more details of Yanfei Xu here:
Acknowledgement from Yanfei Xu: This work was funded by the Faculty Startup Fund support from the University of Massachusetts Amherst awarded to Y.X., the National Science Foundation (award number 2312559) awarded to Y.X., the National Science Foundation (award numbers ECCS-1934977 and ECCS-2246564) awarded to S.H., the Air Force Office of Scientific Research (grant FA9550-22-1-0408) awarded to S.H., the National Science Foundation (award number CBET-1943813) awarded to J.L., the National Science Foundation (award number DMR-2118448) awarded to M. L., and the National Science Foundation (convergence accelerator award number 2235945) awarded to M.L. Work at Oak Ridge National Laboratory Spallation Neutron Source was sponsored by the Scientific User Facilities Division, Office of Basic Energy Sciences of the US Department of Energy. Oak Ridge National Laboratory is managed by UT-Battelle LLC for US DOE under contract no. DEAC05-00OR22725. The beam time was allocated to BASIS on proposal number IPTS-31174. This research used resources of the Advanced Photon Source, a US Department of Energy (DOE) Office of Science user facility at Argonne National Laboratory and is based on research supported by the US DOE Office of Science-Basic Energy Sciences, under contract no. DE-AC02-06CH11357. Electron microscopy was performed at the Center for Nanophase Materials Sciences (CNMS), which is a US Department of Energy, Office of Science User Facility at Oak Ridge National Laboratory.
How do defective filler differ from what might be observed with perfect graphite?
Efficient interfacial heat transfer between polymers and fillers in composites is commonly attributed to denser packing of polymer chains on the fillers’ surfaces, shorter distances between chains and the fillers’ surfaces, higher thermal conductivity of fillers (e.g., perfect fillers such as graphite), and smoother surface textures of perfect fillers. These characteristics are generally believed to promote interfacial thermal transport.
Could you explain the key mechanisms through which defective graphite oxide improves heat transfer properties in polymer composites?
However, our experimental and theoretical studies reveal that defective fillers—despite exhibiting looser packing of polymer chains on the fillers’ surfaces, increased distances between chains and the fillers’ surfaces, lower thermal conductivity of fillers (e.g., defective fillers such as graphite oxide), and rougher surface textures of defective fillers—can enable higher interfacial heat transfer compared to their perfect fillers.
The key lies in the nature of the defective fillers themselves. As defective fillers, graphite oxide contains oxygen-related groups that enable vibrational couplings between its functional groups and atoms in the polymer (PVA) chains at the filler–polymer interfaces. These couplings act as thermal bridges, facilitating more efficient heat flow through the composite. In contrast, perfect graphite–PVA composites lack these types of interfacial vibrational couplings, resulting in lower thermal conductivity.
What methods did you use to introduce or characterise the defects in the graphite oxide structure
A modified Hummers method was used to introduce defects in the perfect fillers (graphite), which led to defective fillers (graphite oxide).
X-ray scattering, neutron scattering, Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, atomic force microscopy, transmission electron microscopy, and scanning electron microscopy were used to characterize the defects structures in the graphite oxide.
how do those defects contribute to more efficient thermal conductivity pathways
In certain cases, defects function as microscopic bridging sites that enhance coupling at the interface, thereby improving thermal transport.
Were there any surprising findings about the extent to which defects (as opposed to perfect crystalline structures) can enhance heat conduction in composites, and how do these insights challenge conventional assumptions?
Efficient interfacial heat transfer in polymer–filler composites is typically attributed to several key characteristics: denser packing of polymer chains at the filler surface, shorter chain-to-filler surface distances, higher intrinsic thermal conductivity of fillers (e.g., graphite), and smoother surface textures. These features are thought to facilitate interfacial thermal transport.
However, our experimental and theoretical investigations reveal that defective fillers—despite exhibiting looser chain packing, greater chain-to-filler surface distances, lower thermal conductivity (e.g., graphite oxide), and rougher surface textures—can enable even more efficient interfacial heat transfer than their perfect counterpart, graphite.
What are the potential industrial or commercial applications where these polymer composites could have the greatest impact, particularly in heat management or thermal regulation?
Polymer composites developed for enhanced thermal transport hold significant potential across a wide range of industrial and commercial applications. These materials play a critical role in modern technologies such as electronics, optics, computer chips, power electronics, batteries, soft robotics, and aerospace systems, where efficient heat dissipation is essential to prevent overheating.
But the technology isn’t limited to high-performance devices like batteries and soft robotics—we’re also exploring its potential in thermal therapy and biomedical applications. In healthcare, precise temperature control is essential for treatments such as post-cardiac arrest cooling, therapeutic hypothermia for stroke, and targeted heating in cancer therapy. With the rise of wearable, flexible polymer-based devices offering controllable and enhanced interfacial thermal transport, clinicians may soon have access to safer, more efficient tools for regulating patient temperature—opening new frontiers in accurate, responsive, and temperature-controlled medical care.
How scalable is the process for integrating defective graphite oxide into polymers at an industrial level, and what are the main challenges you anticipate in transitioning from lab-scale research to large-scale manufacturing?
Since the fillers and polymers are commercial, it is scalable for integrating defective graphite oxide into polymers at an industrial level.
Looking ahead, what are the next steps or areas of research in refining these composites, and are there ongoing collaborations or initiatives aimed at demonstrating their performance in real-world products?
Our work addresses both fundamental and applied challenges in thermal transport in soft matter, with a particular focus on polymers. On the fundamental side, we aim to advance the understanding of thermal transport mechanisms in polymeric materials—investigating how molecular structures and chain dynamics influence thermal conductivity. These insights will enable the rational design of polymers with enhanced thermal performance and help push the boundaries of thermal transport, including achieving ultrahigh or ultralow thermal conductivity and switchable thermal conductivity—capabilities that remain unattainable in existing materials.
On the applied front, we integrate cutting-edge polymer science, thermal transport physics, and engineering to create impactful solutions for real-world applications. In collaboration with industry and clinical partners, we are scaling up polymer composites and validating their thermal performance in demanding environments—from high-performance electronics to advanced healthcare technologies.
Polymers offer a unique combination of flexibility, light weight, wearability, and chemical resistance—properties that traditional materials cannot achieve. These advantages position polymers as promising candidates for next-generation thermal management. In electronics and optics, they serve as effective thermal interface materials, improving heat dissipation and system reliability. In healthcare, they enable novel applications in thermal therapy, temperature-regulating wearables, and thermal imaging—providing patient-friendly solutions that deliver targeted cooling or heating, enhance comfort, accelerate healing, and support personalized treatments. For instance, wearable cooling systems can be used post-cardiac arrest to protect the brain and vital organs by precisely controlling body temperature.
Looking ahead, we envision a future where thermal control is revolutionized by purposefully designed polymers—rooted in the principles of thermal transport physics, polymer science, and mechanical engineering, and engineered to meet the needs of an increasingly dynamic and technologically driven world.
Hassan graduated with a Master’s degree in Chemical Engineering from the University of Chester (UK). He currently works as a design engineering consultant for one of the largest engineering firms in the world along with being an associate member of the Institute of Chemical Engineers (IChemE).
