Engineering performance through geometry: A comparative analysis of swcnts vs. Mwcnts

Single-walled and multi-walled carbon nanotubes (SWCNTs and MWCNTs) represent distinct forms of carbon nanostructures whose geometric differences have profound implications on their properties and engineering performance. This paper provides a comprehensive comparative analysis of SWCNTs versus MWCNTs, emphasizing how structural dissimilarities impact their applications in electronics, composite materials, energy storage and thermal management. We review recent findings (2020–2025) from high-quality literature to elucidate differences in diameter, wall structure, electrical/thermal conductivities, mechanical strength and processing. SWCNTs consist of a single graphene cylinder with diameters ~1–2 nm, whereas MWCNTs comprise multiple concentric graphene cylinders with outer diameters up to tens of nanometers. These geometric distinctions lead to different performance outcomes. For example, SWCNTs can exhibit exceptional electrical conductivity or semiconducting behavior (depending on chirality) and ultra-high flexibility, making them ideal for nanoscale electronics, sensors and flexible devices. In contrast, the robust multi-layer structure of MWCNTs lends them higher bulk thermal stability and ease of bulk production, favouring their use in structural composites, bulk conductive additives and thermal interfaces. We include figures illustrating the structural differences and tabulated comparisons of key properties and use-cases. Application-driven discussions demonstrate that the choice between SWCNTs and MWCNTs is often a trade-off between performance and practicality. While SWCNTs offer superior properties per unit and more predictable behavior at the nanoscale, MWCNTs are more readily available at scale and cost-effective for many industrial uses. The paper concludes that SWCNTs and MWCNTs offer complementary strengths. SWCNTs deliver exceptional properties for high-performance electronics, sensors, and thermal systems, while MWCNTs provide robustness, scalability, and cost-efficiency suited for composites, energy storage, and structural applications. As fabrication and integration methods improve, hybrid systems using both forms are likely to emerge. The future of CNTs lies not in choosing one over the other, but in combining their advantages to unlock new possibilities across engineering and industrial domains.