Metal-Free Catalyst, Fast Curing, Stretchable, Self-Healing Siloxane Modified Polyurea Elastomer with Tunable Properties Based on Hydrogen Bonds

In the past decade, self-healing polymer materials, being researched and utilized in many fields, have attracted more and more attention. In this work, self-healing siloxane elastomer (SPUR) with flexible cross-linked networks were designed through the reaction of amino-functionalized polyether, isocyanate and alpha-siloxane, which endowed elastomer with intermolecular hydrogen bond. Herein, these hydrogen bonds can break and reorganize via a simple thermal treatment to gain self-healing and post-processing actions. The self-healing performance of the elastomer is confirmed through tensile test and SEM surface analysis. Consistent with our experiments, the researches show that siloxane modified polyurea elastomers (SPUR) congaing higher content of amino-functionalized polyether with 2000 molecular weights (PEA20) show much better flexibility and healing efficiency. Also, the polyurea can be quickly cured without any metal catalyst due to the presence of alpha-siloxane, which is a highlight of this article, and it is better than the related literature reported so far. Through tensile test and healing performance test, SPUR1 possessing the both remarkable strength and elasticity was obtained (elongation at break 530 %, tensile stress 5.26 MPa). In addition, it has relatively satisfied healing efficiency 30 % and excellent thermal stability. In view of such intermolecular hydrogen bond, we have developed a special self-healing polymer material with tunable performance by varying the monomer ratio between amino-functionalized polyether PEA9 (the molecular weight Mn=900 Da) and PEA20 (Mn=2000 Da). A variety of self-healing polymer materials can be lightly synthesized on account of the wide extent of commercial activities of raw materials such as primary amine, silane and isocyanate. Therefore, self-healable polymer elastomers are exceptionally popular in a rank of fields, such as coatings, construction, aerospace, flexible electronics, automobile, medical device and lithium-ion batteries.