Self healing conductive materials are recently in strong demand due to their ability to eliminate the fragility, fatigue strength, and weakness of contacts with a metal conductor of currently used soft electronic devices. In particular, polymers with reformable covalent bonds, such as Silly-Putty-like polyborosiloxane (PBS), provide unlimited self-healing capability, and the functionality of the material is given by conductive carbon filler. To implement the self-healing purpose, such polymers possess viscoelasticity for relatively high mobility of chain segments. Therefore, the combination of both polymer matrix and filler imparts viscoelastic material properties, difference in behavior at various deformation and time scales which is essential to consider, whereas in most cases, research focused on integrity restoration of a broken device only, providing scarce rheological data.<br/><br/>Here, we thoroughly studied two critical aspects of such viscoelastic blends. First, influence of relaxation time of PDMS-based polymer matrices on materials properties. Second, role of carbon filler with different aspect ratios in viscoelastic PBS matrix. We investigated relaxation processes of polymer and filler in blends, internal microstructure, and variety of mechanical responses on large and small time scales. In addition, we examined self-healing kinetics of composites through simultaneous rheological and EIS measurements <i>in situ</i>. The study allows one to comprehend the internal processes occurring in carbon viscoelastic blends, define their limits, and better choose a material for specific applications. Moreover, the study allowed to achieve solvent-free printability of composites using melt-electrowriting technique. That gives researchers an ability to fabricate a device with a specific design accordingly to necessary applications, avoiding problems of traditional printing techniques.

Viscoelasticity and melt-electrowriting of self healing carbon – silly-putty composites

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