Self-healing isocyanate microcapsules for efficient restoration of fracture damage of polyurethane and epoxy resins

• Published in: Journal of materials science 2019-06, Vol.54 (11), p.8262-8275
• Main Authors: He, Zhenglong, Jiang, Shuai, An, Na, Li, Xudong, Li, Qifeng, Wang, Junwei, Zhao, Yuhua, Kang, Maoqing
• Format: Article
• Language: English
• Subjects: Building materials; Characterization and Evaluation of Materials; Chemistry and Materials Science; Classical Mechanics; Composites; Crystallography and Scattering Methods; Diisocyanates; Epoxy resins; Fracture toughness; Isocyanates; Materials Science; Polymer matrix composites; Polymer Sciences; Polymers; Polyurethane resins; Self healing materials; Solid Mechanics
• ISSN: 0022-2461; 1573-4803
• DOI: 10.1007/s10853-018-03236-3

Isophorone diisocyanate-loaded microcapsules were synthesized with controllable size for self-healing of structural polymer materials. The obtained microcapsules showed good compatibility with polymer resins, e.g., one-component epoxy and multi-component polyurethane/water glass structural materials. During the processing of composite self-healing materials, the highly cross-linked composite capsule wall ensured the integrity of microcapsules and prevented the leakage and degradation of reactive liquid isocyanates effectively. A relatively larger amount of self-healing agent could be released to the local cracks with the increasing size and content of microcapsules in polymer matrix which improved the self-healing efficiency of the composites. Based on the microcapsules with a diameter of ~96 μm, the healing efficiency of epoxy composites containing 15 wt% of capsules and polyurethane/water glass composites containing 20 wt% of capsules could reach to 105 and 101% recovery of fracture toughness, respectively. The crack-healing effect was further verified by scanning electron microscopy. Meanwhile, a possible self-healing mechanism of microcapsules to the cracks of composite polymer materials was proposed.