POS2-0801
Balancing Toughness and Self-Healing in Disulfide-Containing PI/PU Blends through Dynamic Network Engineering
Topic
S2. High-End Characterization/Polymer Physics/Properties
When and Where
Sep 29, 2026
08:30 - 09:30
Room 301 (Grand Ballroom)
Session Chairs
Hae Jung SON
Boseok KANG
Presenter(s)
Somi Yoon (Hanyang University, Korea Institute of Science and Technology)
Co-Author(s)
Abstract
Self-healable polyimides are promising high-performance polymers, but enhancing healing efficiency typically requires increased chain mobility, which often compromises mechanical strength and thermal stability. To overcome this trade-off, we developed disulfide-containing polyimide/polyurethane (PI/PU) blends by introducing a dynamic polyurethane phase into a self-healable polyimide matrix. PI/PU blends with 0, 1, 3, 5, 10, 30, and 100 wt% PU were prepared to examine the effect of composition on thermal transition behavior and mechanical performance. Flexible PU chains promoted segmental relaxation in the rigid PI matrix, decreasing the glass transition temperature (Tg) from 94.6 °C for pristine PI to 82.0 °C for PIPU10. This Tg reduction is expected to facilitate chain diffusion and interfacial rearrangement during thermal healing. In addition, disulfide bonds in both PI and PU can undergo dynamic covalent exchange above Tg, enabling network rearrangement and structural recovery at damaged regions. Among the compositions, PIPU10 showed the most favorable structure-property relationship. Its ultimate tensile strength was maintained and slightly increased from 71.42 to 73.21 MPa, while toughness increased from 1.32 to 2.96 MPa, corresponding to more than a two-fold enhancement. The moderate incorporation of PU improved the balance between rigidity and deformability, enhancing energy dissipation without sacrificing tensile strength. This toughening effect is attributed to the synergistic contribution of rigid PI domains, deformable PU-rich regions, and reversible disulfide linkages, which suppress crack propagation and promote structural recovery. These results demonstrate that dynamic PI/PU blending is an effective strategy for improving toughness and self-healing capability while mitigating the conventional trade-off between healing efficiency and mechanical performance in polyimide-based materials.
