High-adhesion PDMS/Ag conductive composites for flexible hybrid integration

The integration of silicon chips and other rigid components on soft polymeric substrate represents a viable option towards mass production of high-performance stretchable electronics, where bonding materials with high stretchability, high conductivity, and high adhesion strength become the key in the process. Polydimethylsiloxane/silver composites (PDMS/Ag) are promising candidates, but the adhesion of PDMS-based composites is usually too weak to be useful. Herein, we report a “netting and anchoring” strategy, in which a small amount of polyborosiloxane (PBS) prepolymer is added and the formed PBS networks not only net the PDMS networks with dense physical entanglements but also anchor PDMS networks to adherent surfaces with reversible bonds. The obtained composites have an adhesion strength of 2.87 MPa (8.2 times and 3.2 times higher than that of the untreated and conventional silane-treated composites) and maintain a high conductivity of 1.3 × 10−4 Ω·cm. The enhanced bonding originates from three aspects: good wettability, uniform interfacial bonding, and stress transfer from the interface to the bulk to elicit bulk energy dissipation. As an example, a stretchable temperature sensor system integrated with this strategy can resist up to 70% stretching, bending, and twisting.