PDMS-Silver Nanocomposite For Bendable And Stretchable Conductive Stripes

Abstract

In this research, a simple and low-cost protocol for fabricating PDMS-silver composite as flexible conductive polymer is presented. Rod-shaped silver acetate (RS-AcOAg) was synthesized and fabricated into a solvent-cast RS-AcOAg film. The film was thermally decomposed into porous silver structures at 300ºC. The thermal decomposition of RS-AcOAg film induced the formation of silver microparticles (AgNPs) on the surface of RS-AcOAg with the expense of RS-AcOAg rod. AgNPs sintered into bigger particles and turned RS-AcOAg film into porous silver film consisting of interconnected quasi-sphere silver microparticles (AgMPs). The sintered structures transformed porous silver into rigid structures and affected the electrical resistivity due to the cracked structures when mechanical strain was applied. To suppress the sintering of the AgMPs, polydimethylsiloxane base (bPDMS) was coated on the surface of RS-AcOAg before the thermal decomposition. The bPDMS decreased mobility of AgMPs and suppressed the sintering. The porous silver film with and without bPDMS-suppressed sintering consisted of AgMPs with particle size of ~240 nm and ~950 nm, respectively. Commercial columnar silver acetate (CC-AcOAg) was employed for comparison purpose. The porous silver film with bPDMS-suppressed sintering strongly embedded onto the surface of polydimethylsiloxane (PDMS) as PDMS-silver composite, exhibited excellent mechanical properties with high conductivity under mechanical strain, including stretching, bending, and twisting. An application of PDMS-silver composite as a flexible conductive strip to use as strain sensor for robotic hand was demonstrated.