A highly stretchable and conductive continuous composite filament with buckled polypyrrole coating for stretchy electronic textiles

• An intrinsically stretchable (100% strain) PPy coating was achieved. • The buckled PPy coated PU fiber (PU@bPPy) was continuously fabricated by post-drawing method. • PU@bPPy showed a high and ultra-stable conductance (529 S/m, 3.5 % Δ R / R 0 at 50 % strain, 6500 cycles). • PU@bPPy as stretchable circuits and heaters showed good stability and repeatability. Highly stretchable and conductive fibers as crucial components for stretchy electronic textiles have developed rapidly in recent years, benefiting from the design of stretchable structures. However, routes toward continuous production via simpler fabrication processes remain a huge challenge that has greatly limited its widespread application. In this work, we reported an intrinsically stretchable multifilament with both highly stretchable and conductive (537 S m −1 under 100 % strain) polypyrrole (PPy) coating enhanced by sodium sulfosalicylate (NaSSA) as a dopant. Based on this, a post-drawing method was further proposed to continuously fabricate stretchable conductors with PPy buckling on surface. The PU multifilament with buckle PPy coating (PU@bPPy) exhibited a high and ultra-stable conductance, showing initial conductivity at 529 S m −1 and only 3.5 % change in resistance after > 6500 stretching cycles at 50 % strain. Moreover, the PU@bPPy could be easily integrated into electronic textiles as stretchable electronic circuits and stretchable joule heaters.