Enhanced Strength and Toughness of Poly(Siloxane‐Urea) Elastomers Through Rigid Nanostructured Reinforcement Between Incompatible Soft Phases

ABSTRACT Achieving high flexibility, toughness, healability, and recyclability in silicone‐based elastomers remains a key challenge, mainly due to the non‐polar nature and weak molecular interactions of polydimethylsiloxane (PDMS). Herein, we propose a design strategy combining rigid nanostructured reinforcement with dual soft‐segment microphase separation, significantly enhancing the mechanical strength (21.6 MPa), toughness (102.8 MJ m −3 ), puncture resistance, and damage tolerance (fracture energy = 32.9 kJ m −2 ) of poly(siloxane‐urea) elastomers. Specifically, by introducing structurally complementary heterogeneous hard segments, acylsemicarbazide units, which are linked by benzene rings and regulated by FH bonds, form nano‐scale hydrogen‐bonded arrays characterized by small size and dense stacking. The hydrogen‐bonded arrays act as dynamic crosslinks, surrounded by the poly(propylene glycol) phase and then uniformly dispersed in the PDMS phase. These hydrogen‐bonded arrays, when combined with the forced compatibility and spontaneous separation of the dual soft phases, can effectively dissipate energy under stress, particularly at the crack tip. Moreover, the electron‐withdrawing effect of the fluorinated groups and the dynamics of the hydrogen‐bonded arrays together promote the dissociation and recombination of the hard phase regions, which endows the material with good healability and reprocessability.