Review of sustainable, eco-friendly, and conductive polymer nanocomposites for electronic and thermal applications: current status and future prospects

Biodegradable polymer nanocomposites (BPNCs) are advanced materials that have gained significant attention over the past 20 years due to their advantages over conventional polymers. BPNCs are eco-friendly, cost-effective, contamination-resistant, and tailorable for specific applications. Nevertheless, their usage is limited due to their unsatisfactory physical and mechanical properties. To improve these properties, nanofillers are incorporated into natural polymer matrices, to enhance mechanical durability, biodegradability, electrical conductivity, dielectric, and thermal properties. Despite the significant advances in the development of BPNCs over the last decades, our understanding of their dielectric, thermal, and electrical conductivity is still far from complete. This review paper aims to provide comprehensive insights into the fundamental principles behind these properties, the main synthesis, and characterization methods, and their functionality and performance. Moreover, the role of nanofillers in strength, permeability, thermal stability, biodegradability, heat transport, and electrical conductivity is discussed. Additionally, the paper explores the applications, challenges, and opportunities of BPNCs for electronic devices, thermal management, and food packaging. Finally, this paper highlights the benefits of BPNCs as biodegradable and biodecomposable functional materials to replace traditional plastics. Finally, the contemporary industrial advances based on an overview of the main stakeholders and recently commercialized products are addressed.

Fabrication of thermally conductive polymer composites based on hexagonal boron nitride: recent progresses and prospects

Hexagonal boron nitride (h-BN) and its nanomaterials are among the most promising candidates for use in thermal management applications because of their high thermal conductivity, thermal stability, and good electric insulation, and when used as the conductive fillers, they enhance the overall properties of polymer composites. In this review, the basic concepts of h-BN are introduced, followed by the synthesis of BN nanotubes and BN nanosheets. Then, various novel methods to fabricate h-BN polymer composites with improved thermally conductive paths are discussed. They can be classified into two categories: dispersion and compatibility reinforced and structure formation. In addition, the thermal conducting mechanisms of h-BN composites are proposed. Finally, the advantages and limitations of aforementioned strategies are summarized.

Tailoring the Thermal Conductivity of Rubber Nanocomposites by Inorganic Systems: Opportunities and Challenges for Their Application in Tires Formulation

The development of effective thermally conductive rubber nanocomposites for heat management represents a tricky point for several modern technologies, ranging from electronic devices to the tire industry. Since rubber materials generally exhibit poor thermal transfer, the addition of high loadings of different carbon-based or inorganic thermally conductive fillers is mandatory to achieve satisfactory heat dissipation performance. However, this dramatically alters the mechanical behavior of the final materials, representing a real limitation to their application. Moreover, upon fillers’ incorporation into the polymer matrix, interfacial thermal resistance arises due to differences between the phonon spectra and scattering at the hybrid interface between the phases. Thus, a suitable filler functionalization is required to avoid discontinuities in the thermal transfer. In this challenging scenario, the present review aims at summarizing the most recent efforts to improve the thermal conductivity of rubber nanocomposites by exploiting, in particular, inorganic and hybrid filler systems, focusing on those that may guarantee a viable transfer of lab-scale formulations to technological applicable solutions. The intrinsic relationship among the filler’s loading, structure, morphology, and interfacial features and the heat transfer in the rubber matrix will be explored in depth, with the ambition of providing some methodological tools for a more profitable design of thermally conductive rubber nanocomposites, especially those for the formulation of tires.

Recently Emerging Nanotechnological Advancements in Polymer Nanocomposite Coatings for Anti-corrosion, Anti-fouling and Self-healing

Recent nanotechnological advancements have enabled novel innovations in protective polymer nanocomposites (PNC) coatings for anti-corrosion, anti-fouling and self-healing services on material surfaces. Nanotechnology encompases research, manufacturing, and application of nanoparticulate architectures, tubular structures, sheets or plates exhibiting sizes below 100 nanometers (nm) in at least a single dimension. Inclusions of nanoparticles into organic entities have demonstrated enhanced properties essential for attainiment of aesthetics, anti-corrosion, thermal stability for high-temperature performances, mechanical strength essential for resisting coating deterioration in harsh environments, nano-architectural cross-linking capable of hindering penetration of corrosive, and biofouling entities. Unlike previously published literature, this paper elucidates very recently emerging important advancements in novel techniques utilized in developing PNC coatings for applications in aerospace, packaging, automotive, biomedicine, maritime, and oil and gas industries for attaining superior anti-fouling, anti-corrosion, and self-healing behaviors on critical material surfaces. Emerging market structures and novel applications are also presented.

An Approach Towards Optimization Appraisal of Thermal Conductivity of Magnetic Thermoplastic Elastomeric Nanocomposites Using Response Surface Methodology

This study investigates the optimization of thermal conductivity of nickel zinc ferrite incorporated thermoplastic natural rubber nanocomposites using response surface methodology (RSM). The experimental runs were based on face-centered central composite design (FCCD) where three levels were designated for both temperature and magnetic filler content. The analysis of variance (ANOVA) results showed that the implemented technique is significant with an F-value of 35.7 and a p-value of <0.0001. Moreover, the statistical inference drawn from the quadratic model suggests a saddle response behavior the thermal conductivity took when both factors were correlated. The factors’ optimal set confined within the practical range led to a thermal conductivity of 1.05 W/m·K, a value which is believed to be associated with an optimal percolated network that served as efficacious thermal pathways in the fabricated nanocomposites. These results are believed to contribute to the potential employability of magnetic polymer nanocomposites (MPNCs) in electronic packaging applications.

Globular Flower-Like Reduced Graphene Oxide Design for Enhancing Thermally Conductive Properties of Silicone-Based Spherical Alumina Composites

The enhancement of thermally conductive performances for lightweight thermal interface materials is a long-term effort. The superb micro-structures of the thermal conductivity enhancer have an important impact on increasing thermal conductivity and decreasing thermal resistance. Here, globular flower-like reduced graphene oxide (GFRGO) is designed by the self-assembly of reduced graphene oxide (RGO) sheets, under the assistance of a binder via the spray-assisted method for silicone-based spherical alumina (S-Al₂O₃) composites. When the total filler content is fixed at 84 wt%, silicone-based S-Al₂O₃ composites with 1 wt% of GFRGO exhibit a much more significant increase in thermal conductivity, reduction in thermal resistance and reinforcement in thermal management capability than that of without graphene. Meanwhile, GFRGO is obviously superior to that of their RGO counterparts. Compared with RGO sheets, GFRGO spheres which are well-distributed between the S-Al₂O₃ fillers and well-dispersed in the matrix can build three-dimensional and isotropic thermally conductive networks more effectively with S-Al₂O₃ in the matrix, and this minimizes the thermal boundary resistance among components, owning to its structural characteristics. As with RGO, the introduction of GFRGO is helpful when decreasing the density of silicone-based S-Al₂O₃ composites. These attractive results suggest that the strategy opens new opportunities for fabricating practical, high-performance and light-weight filler-type thermal interface materials.

Dense Vertically Aligned Copper Nanowire Composites as High Performance Thermal Interface Materials

Thermal interface materials (TIMs) are essential for managing heat in modern electronics, and nanocomposite TIMs can offer critical improvements. Here, we demonstrate thermally conductive, mechanically compliant TIMs based on dense, vertically aligned copper nanowires (CuNWs) embedded into polymer matrices. We evaluate the thermal and mechanical characteristics of 20-25% dense CuNW arrays with and without polydimethylsiloxane infiltration. The thermal resistance achieved is below 5 mm² K W^-1, over an order of magnitude lower than commercial heat sink compounds. Nanoindentation reveals that the nonlinear deformation mechanics of this TIM are influenced by both the CuNW morphology and the polymer matrix. We also implement a flip-chip bonding protocol to directly attach CuNW composites to copper surfaces, as required in many thermal architectures. Thus, we demonstrate a rational design strategy for nanocomposite TIMs that simultaneously retain the high thermal conductivity of aligned CuNWs and the mechanical compliance of a polymer.