Biocompatible conductive polymers with high conductivity and high stretchability.

Stretchable electronic materials have attracted great attentions due to their important applications in areas such as bioelectronics, wearable electronics and soft robotics. Stretchable electrode is an indispensable unit of stretchable devices or systems. Intrinsically conductive polymers like poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) can have high mechanical flexibility and good biocompatibility. But their electrical conductivity and mechanical stretchability should be greatly improved for their applications as stretchable electrode. Here, we report highly conductive and highly stretchable PEDOT:PSS by incorporating biocompatible D-sorbitol. D-sorbitol can serve as both secondary dopant and plasticiser for PEDOT:PSS. It can not only significantly enhance the conductivity but also the stretchability. D-sorbitol-PEDOT:PSS (s-PEDOT:PSS) can have a conductivity of >1000 S/cm, and the conductivity could be maintained at a strain up to 60%. The resistance of s-PEDOT:PSS remains almost constant during repeated stretching-releasing cycles. The mechanism for the stretchability improvement by D-sorbitol is ascribed to the softening of PSSH chains. D-sorbitol can position among the PSSH chains and thus destructs the hydrogen bonds among the PSSH chains. This makes the conformational change of the PSSH chains under stress become easy and thus increases the mechanical flexibility of PEDOT:PSS. This conductivity is the highest for biocompatible intrinsically conductive polymers with high stretchability.