Electro-Responsive Thermochromic and Mechanically Enhanced CNT Yarns through Solution Blow Spinning Encapsulation

Carbon nanotube (CNT) yarns combine textile adaptability, conductivity, and electrothermal functionality, positioning them as a key material for advancing flexible smart fabrics, particularly in electrothermal applications. However, their widespread use is hindered by safety concerns related to exposed CNT yarns acting as electrical heating elements and their intrinsic black color, which limits aesthetic flexibility in textile design. Therefore, flexible encapsulation of CNTs is essential for unlocking their full industrial potential. This study demonstrates the successful application of solution blow spinning (SBS) technology for encapsulating CNT yarns, emphasizing its scalability and efficiency in producing flexible, electro-responsive conductive yarns with significantly enhanced mechanical properties. Various polymers, including ultrahigh molecular weight polyethylene (UHMWPE), polylactic acid (PLA), polyacrylonitrile (PAN), and polyvinylidene fluoride (PVDF), are explored for encapsulating CNT yarns, significantly reducing the risk of electrical exposure and providing tunable color options by effectively covering the yarns' intrinsic blackness. SBS also enhances yarn performance and durability. Among them, C-PE (CNT core with UHMWPE sheath) exhibits a remarkable improvement in abrasion resistance, with the cycle count increasing from 35 to 3115. C-PVDF (CNT core with PVDF sheath) demonstrates significant improvements in elongation, increasing from 42.8% to 63.6%. Furthermore, incorporating thermochromic-enhanced polymers enables real-time temperature visualization, offering both functional and aesthetic versatility. These advancements pave the way for high-performance, multifunctional smart textiles tailored for wearable electronic applications.