Self‐Healing and Electrical Properties of Viscoelastic Polymer–Carbon Blends

Abstract

Self-healing polymer-carbon composites are seen as promising materials for future electronic devices, which must be able to restore not only their structural integrity but also electrical performance after cracking and wear. Despite multiple reports about self-healing conductive elements, there is a lack of a broad fundamental understanding of correlation between viscoelasticity of such composites, their electrical properties, and self-healing of their mechanical as well as electrical properties. Here, it is reported thorough investigation of electromechanical properties of blends of carbon black (CB) as conductive filler and viscoelastic polymers (polydimethylsiloxanes (PDMS) and polyborosiloxane (PBS)) with different relaxation times as matrices. It is shown that behavior of composites depends strongly on the viscoelastic properties of polymers. Low molecular polymer composite possesses high conductivity due to strong filler network formation, quick electrical, and mechanical properties restoration, but for this the ability is sacrificed to flow and ductility at large deformation (material is brittle). In contrary, high relaxation time polymer composite behaves elastically on small time and flows at large time scale due to weak filler network and can heal. However, the electrical properties are worse than that of carbon and viscous polymer and degrade with time.

Self-healable printed magnetic field sensors using alternating magnetic fields

“…The cured composites exhibit higher storage moduli than loss moduli over the whole range of frequency (Supplementary Fig. 3 ), revealing an elastic behavior and mechanical stability (i.e., no flowing) over long time scales which is in agreement with the previous reports 29 , 32 , 33 . When applying AMF (of 50 Hz frequency and <130 mT amplitude, see Supplementary Fig.…”

Reversibly Photoswitchable High‐Aspect Ratio Surfaces

“…The aggregated particles render the polymer's flow behavior with flow threshold points. [ 24 ] Such blends show elastic behavior over a very broad time‐scale range and nearly do not flow when small stress is applied. The blends start to flow when the stress above a threshold value is applied.…”

“…The blends start to flow when the stress above a threshold value is applied. [ 24 ] Such kind of behavior makes the control of the flow behavior of polymers difficult. Therefore, in order to avoid these difficulties, we used a two‐step approach—deposited polymer first and light‐absorbing material next.…”