Multivalent urea bond assembly of polyacrylate oligomers with improved mechanical strength and high self-healing efficiency

The self-healing and stretchable polyacrylate oligomers based on multivalent urea bonds were synthesized through the cross-linking of polyacrylate prepolymers and polyurea trimer. The variable temperature FT-IR and oscillatory rheometer analysis testified the excellent repeatability of multivalent urea bonds. Good thermal stability of the self-healing samples were proved by TGA. The length of the polymer branch and crosslink density of each sample could provide different thermodynamic properties which were confirmed by DSC and DMA. Meanwhile, the cross-linked polyacrylate oligomers without any catalyst or external intervention showed multiple self-repairs, scratch repair capabilities and high self-healing efficiency which was confirmed by the optical microscopy and the stress–strain testing. The maximum tensile strength of the pristine sample was as high as 7.8 MPa. Moreover, the oligomers showed self-repair repeatedly at room temperature and rapidly restored to 95% of the original tensile strength at 50 °C. Thus, the type of cross-linked polyacrylate oligomers might have high potential for further research in medicine, resin and plastics applications.