Jeonbuk Researchers Advance Segregated Composite Fabrication and Modeling

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Modern portable and wearable electronic devices increasingly integrate high-performance components and wireless communication technologies. While this integration enhances functionality, it also raises the risk of electromagnetic interference (EMI) and heat accumulation, both of which can degrade device performance and reliability. As a result, there is growing demand for advanced materials capable of simultaneously managing electrical interference and dissipating heat efficiently.

Segregated conductive polymer composites (S-CPCs) have emerged as promising candidates for such applications. These three-dimensional polymer materials contain networks of conductive fillers concentrated along polymer boundaries, allowing them to achieve high electrical and thermal conductivity even with relatively small amounts of filler. However, despite their potential, practical use of S-CPCs has been limited. Existing theoretical models do not adequately account for their unique internal structures, making effective design difficult. In addition, S-CPCs tend to form microscopic voids during fabrication, which restrict the amount of filler that can be added and weaken mechanical strength.

To overcome these challenges, a research team led by Professor Seong Yun Kim from the Department of Organic Materials and Fiber Engineering at Jeonbuk National University, South Korea, has developed a novel fabrication strategy together with advanced predictive models tailored for segregated composites. "We employed a processing strategy that takes advantage of differences in melting points between commercial polymers to suppress micro-void formation, and we established a new conductivity prediction model that reflects the unique structure of segregated composites," explains Prof. Kim. The study was published in Volume 8 of Advanced Composites and Hybrid Materials on December 2, 2025.

In their experiments, the researchers used polypropylene (PP), which melts at 150 °C, and blended it with a PP terpolymer that melts at a lower temperature of 130 °C. Two types of S-CPCs were fabricated: one using graphitic nanoplatelets (GNPs) as conductive fillers, referred to as G-SCs, and another using hexagonal boron nitride (h-BN), referred to as B-SCs. GNPs provide excellent electrical and thermal conductivities, while h-BN offers outstanding electrical insulation alongside high thermal conductivity.

Using micro-computed tomography (μ-CT), the team analyzed the internal structures of the composites and identified two key structural features influencing performance: excluded volume (regions inaccessible to fillers) and micro-voids. Further, they found that an optimal amount of the lower-melting terpolymer minimized micro-void formation, significantly improving mechanical strength as well as electrical and thermal performance.

The optimal formulation of G-SCs and B-SCs were able to incorporate up to 4.93% and 12.15% more filler material, respectively. As a result, the G-SCs exhibited up to 124.07% and 68.11% increase in electrical and thermal conductivity, respectively, while the B-SCs achieved up to a 53.54% improvement in thermal conductivity.

Beyond material fabrication, the researchers incorporated excluded volume and micro-void effects into conventional percolation theory to develop new segregated percolation models. These models accurately predicted the conductive behavior of the composites, and showed strong agreement with experimental results, offering a powerful tool for future material design.

"The materials developed in this study can be immediately utilized as next-generation EMI shielding and thermal management solutions," concludes Prof. Kim. "Moreover, the proposed models will accelerate the design of customized advanced materials across various industries."

Overall, by combining structural optimization with advanced theoretical modeling, this research provides a comprehensive strategy for developing highly conductive polymer composites suitable for next-generation electronic and energy systems.