Biotemplated synthesis of cellulose nanocrystal@PVP-assisted polydopamine@Ag nanoparticle as conductive composites

The controllable deposition of silver (Ag) nanoparticle onto functional materials is beneficial for a wide range of applications including conductive composites and electrically conductive adhesives. While the deposition of Ag nanoparticles on various substrates has been extensively studied, the fine control of the size, dispersion, growth, and colloidal stability of silver nanoparticles on complex high aspect-ratio nanomaterials is still a challenge. In this work, we report the synthesis of conductive composites of cellulose nanocrystal coated with a uniform layer of Ag nanoparticle. For this, we have used polyvinylpyrrolidone (PVP) as a coupling agent for the formation of polydopamine (PDA) on cellulose nanocrystal and the subsequent formation of uniform Ag nanoparticle. With continuously and closely packed Ag nanoparticles, the as-prepared conductive composites demonstrated promising applications as conductive composite paste for direct writing and as a co-filler for hybrid electrically conductive adhesives. As a conductive composite paste, no high-temperature sintering is required when it is written on paper, glass slide and fabrics to form conductive patterns. When served as a co-filler in electrically conductive adhesives, a small amount of conductive composites (1.5 wt%) largely enhanced conductivity and lap shear strength, while maintaining the excellent viscosity for easy operation in stencil printing and 3D printing.