High-Performance PDMS Elastomers Constructed via Oxalyl Dihydrazide for Thermoreversible Bonding in Flexible...

The rapid proliferation of flexible and wearable electronics has imposed stringent requirements on elastomeric substrates, including high mechanical strength, exceptional toughness, reversible adhesion, and reprocessability-properties that conventional covalently crosslinked polydimethylsiloxane (PDMS) elastomers inherently lack due to their permanent networks. Owing to their reversible physical crosslinking and versatile design strategies, hydrogen bonds can endow linear PDMS with a broader spectrum of performance possibilities. However, the construction of hydrogen-bonded PDMS elastomers that simultaneously achieve both outstanding mechanical performance and reversible interfacial adhesion remains a significant challenge. Herein, we report the first design and synthesis of linear PDMS elastomers dynamically crosslinked by dense multiple hydrogen-bonding arrays derived from oxalyl dihydrazide (ODH). A series of silicone poly(urea oxalyl dihydrazide) (SPUOH) elastomers were synthesized via a one-pot method by tailoring the molecular weight of the α, ω-bis (aminopropyl) polydimethylsiloxanes (A-PDMS) and the ODH loading. The synergistic interplay of strong ODH-based hydrogen bonds and weak urea-based hydrogen bonds enables tunable mechanical properties: SPUOH-3k-0.33 achieves a tensile strength of 5.15 MPa, an elongation at break of ∼1200%, and a toughness of 39.8 MJ m-3, substantially surpassing reported linear PDMS elastomers. Rheological and AFM analyses reveal that hydrogen-bond ordering governs thermal resistance and microphase separation, with high ODH loading inducing a phase inversion. Benefiting from thermally reversible hydrogen bonds, SPUOH-3k-0.33 exhibits a lap shear strength of 2.72 MPa on polyamide and maintains performance over 20 cycles. A prototype flexible sensor demonstrates a gauge factor of 4.6 with reliable motion monitoring. This work establishes ODH-based hydrogen-bonding arrays as a versatile platform for high-performance, sustainable, and adhesively integrable PDMS substrates for next-generation flexible electronics.