Washable Few-Layer Graphene-Based Conductive Coating: The Impact of TPU Segmental Structure on Its Final Performances

The development of sustainable, water-based conductive coatings is essential for advancing environmentally responsible wearable and printed electronics. Achieving high electrical conductivity and wash durability remains a key challenge. This is largely dependent on the compatibility between the polymer matrix, the conductive filler and the substrate surface. In this study, a facile formulation strategy is proposed by directly integrating few-layer graphene (FLG, 2.5 wt%) into commercial bio-based thermoplastic polyurethanes (TPUs), combined with polyvinylpyrrolidone (PVP) as a dispersing agent. The investigation focuses on how the segmental architecture of four TPUs with different structure and hard–soft segments composition influences filler dispersion, mechanical integrity, and electrical behavior. Coatings were deposited onto flexible substrates, including textiles and paper, using a bar-coating process and were characterized in terms of morphology, thermal properties, electrical conductivity, and wash resistance. The results demonstrate that TPUs containing a higher presence of hard segments interact more effectively with hydrophobic surfaces, while TPUs with a higher contribution of soft segments improve adhesion to hydrophilic substrates and facilitate the formation of the percolation network, underling the role of TPU microstructure in controlling interfacial interactions and overall coating performance. The proposed comparative approach provides a sustainable pathway toward durable, high-performance, and washable electronic textiles and paper-based devices.