Seoul researchers design TPU with high toughness, notch insensitivity and rapid self-healing

Researchers at Seoul National University have reported a thermoplastic polyurethane (TPU) elastomer that overcomes the trade-off between mechanical toughness, crack resistance and self-healing performance through tailored soft-segment engineering.

The study, published on 12 February 2026 in the International Edition of Angewandte Chemie, was led by Changhoon Yu and Hongdeok Kim, who contributed equally, alongside colleagues at the university’s Department of Materials Science and Engineering and Research Institute of Advanced Materials.

Conventional TPUs rely on hydrogen-bonded urethane hard domains for strength, but these rigid domains typically restrict the chain mobility required for efficient healing. Softer segments provide elasticity, yet are often more susceptible to damage and notch sensitivity. The Korean team addressed this dilemma by incorporating α,ω-hydroxyl end-functionalized polyacrylates into the TPU soft segment, replacing conventional linear alkyl acrylates with branched 2-ethylhexyl acrylate units.

The branched side-chain architecture increases segmental mobility in a temperature-responsive manner, promoting more uniform stress distribution and thermally activated chain rearrangement without compromising the mechanical role of the hard domains.

The resulting acrylic TPU achieved a toughness of 186 MJ·m⁻³ and maintained fracture energy above 197 kJ·m⁻², even at elongations exceeding 900%, demonstrating stable notch performance. In self-healing tests, samples recovered approximately 90% of their original properties after 3 hours at 45°C, indicating practical repair capability under moderate thermal conditions.
According to the authors, the tailored soft-segment strategy suppresses strain-induced domain disruption while enhancing energy dissipation. 

The work suggests that branched polyacrylate-based soft segments may offer a scalable pathway toward TPU elastomers that combine durability, crack tolerance and autonomous healing – attributes relevant to wearable electronics, soft robotics, protective coatings and advanced industrial components.

Diagram © Wiley-VCH GmbH, Weinheim

Angewandte Chemie