A highly stable PI-PU conductive copolymer for wearable

Smart textiles require conductors that maintain electrical stability under repeated deformation and laundering while preserving textile-like softness. Here, we develop a poly(imide-urethane) (PI–PU) copolymer that combines the high-temperature dimensional stability, abrasion, and dielectric properties of polyimide (PI) with the elasticity of polyurethane (PU). The PI–PU copolymer was synthesized from polytetramethylene ether glycol (PTMEG 3000), 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA), and m-xylylene diisocyanate (XDI) in N-methyl-2-pyrrolidone (NMP) under nitrogen; optional melamine crosslinking improved mechanical robustness. Conductive pastes were obtained by dispersing 62 wt% Ag powder in the PI–PU using a high-speed vacuum defoaming mixer. Printed traces on TPU film exhibited a resistivity of 3.5 × 10 -5 Ω·cm and negligible resistance change after 20% elongation and recovery (0–8% variation, best case 0%). After AATCC 135 laundering 50 times, the resistance on knitted and woven laminates increased modestly from ∼2.0–2.8 Ω to 5.1–5.5 Ω, indicating durable conductivity and superior wash-wear resistance compared with a neoprene-based benchmark. The results demonstrate that PI–PU/Ag is a promising platform binder for printed circuits in wearable electronics, enabling stable signal transmission under cyclic strain and laundering. • A new elastic conductive slurry from polymer polymerization, material ratio, homogenization technology, and process design. • The basic slurry in this study is a high-strength elastic PI-PU material with high hardness on the surface, and surface protection is required during use. • The PI-PU elastic conductive paste in this study has lower resistivity (3.5 × 10 -5 Ω‧cm). • The PI-PU copolymer has a lower elastic resistance variation rate (<10%) • The PI-PU conductive slurry has better washing/ resistance (50 times).