Polyborosiloxane-Conjugated Polymer Blends as a Self-Healing Material for Wearable Sensors

The need for durable and flexible electronics is emerging as a high research priority as electronic materials are being integrated into wearable devices for bioelectronic monitoring and sensing applications. Since silicon is rigid and brittle and not suitable for wearable technology, this has led to the use of organic materials as the active layer in flexible devices. However, organic materials still exhibit wear and tear after prolonged use and irreversible damage will lead to decreased device performance and eventual failure. Therefore, new properties need to be introduced to prevent this issue which will hopefully lead to a more reusable society.<br/><br/>Self-healing has received a lot of attention recently and is a strong candidate for improved durability and reusability. A self-healing material can reform and repair damage without the need of outside help and is split up into extrinsic and intrinsic systems. Extrinsic healing is governed by an external source embedded into the material that promotes reformation such as micelles releasing catalysts for new bond formation. Whereas intrinsic healing is governed by functionalities inherent to the structure of the material. A long list of intrinsic moieties have been used for self-healing including hydrogen bonding, ionic interactions, covalent bonding, π-π interactions and supramolecular structures which has lead to promising results. Many of these intrinsic functionalities have been implemented into polymers making them ideal candidates to combine with polymeric organic semiconductors as new self-healing electronic materials.<br/><br/>Herein, we have combined the semiconducting properties of conjugated polymers with polyborosiloxane, a polysiloxane polymer crosslinked with boric acid. Polyborosiloxane intrinsically contains dative B-O bonds enabling a reversible and dynamic system needed for self-healing. Via either blending or crosslinking the two polymers and exploring the electrical characterisation under mechanical stress, our findings show that this new class of viscoelastic materials have potential for durable and wearable electronics.