Crystallization Behavior and Sensing Properties of Bio‐Based Conductive Composite Materials

Abstract

Poly(3‐hydroxyoctanoate) (PHO), a biocompatible polymer with a skin‐like feel produced by bacterial fermentation, is compounded with carbon nanofibers (CNFs) or carbon black (CB), respectively, to form flexible, 3D printable, bio‐based conductive composites. Conductivities up to 10 and 3 S m−1 can be achieved for CNF and CB, respectively, without negatively affecting the composites’ processability. Both filler materials act as nucleating agents for PHO crystallization, significantly accelerating this process which is extremely slow for the filler‐free polymer. Mechanical performance, for example, elastic modulus, is also improved by the addition of CNF or CB. Both types of filler form composites that show a distinct response to mechanical deformation: bending, twisting, and stretching (up to 10% elongation) result in a marked decrease in their electrical resistance (up to 30%). This phenomenon has been exploited to fabricate a 3D‐printed strain sensor that can detect flection and extension via a change in resistance. The results demonstrate the potential of this sustainable biopolymer and its composites for applications in the biomedical space.

Environmentally Benign Fast-Degrading Conductive Composites

“…Most of these devices contain metals (e.g., silver, copper) and fossil-based materials (e.g., printed circuit board), meaning that the end-of-life and toxicity of these devices can become an issue. − To solve this problem green or sustainable electronics are being developed to ameliorate these environmental issues . Typical strategies include the substitution of metal-based conductive inks/materials with sustainably sourced carbon-based conductive materials, such as graphene or carbon nanomaterials, and replacing the body of the device/substrate with biodegradable polymers or natural materials to reduce its impact on the environment. − Recently, Beniwal et al have showed that graphene-based carbon ink could be screen-printed onto a paper substrate to construct a humidity sensor with wireless communication . Additionally, Tu et al have showed that carbon-based inks could be printed onto dissolvable PVA/gelatin substrates for point-of-care testing .…”