Developing an autonomous room temperature self-healing supramolecular
polyurethane (PU) with toughness and stiffness remains a great challenge.
Herein, a novel concept that utilizes a T-shaped chain extender with double
amide hydrogen bonds in a side chain to extend PU prepolymers to construct
highly stiff and tough supramolecular PU with integrated functions is
reported. Mobile side-chain H-bonds afford a large flexibility to modulate
the stiffness of the PUs ranging from highly stiff and tough elastomer
(105.87 MPa Young’s modulus, 27 kJ m−2 tearing energy), to solvent-free
hot-melt adhesive, and coating. The dynamic side-chain multiple H-bonds
afford an autonomous self-healability at room temperature (25 °C). Due to
the rapid reconstruction of hydrogen bonds, this PU adhesive demonstrates
a high adhesion strength, fast curing, reusability, long-term adhesion, and
excellent low-temperature resistance. Intriguingly, the PU emits intrinsic
blue fluorescence presumably owing to the aggregation-induced emission of
tertiary amine domains induced by side-chain H-bonds. The PU is explored
as a counterfeit ink coated on the predesigned pattern, which is visiblelight
invisible and UV-light visible. This work represents a universal and
facile approach to fabricate supertough supramolecular PU with tailorable
functions by chain extension of PU prepolymers with multiple H-bonding
chain extenders.


Yuan Yao,Ziyang Xu,Bo Liu,Meng Xiao,Jianhai Yang,Wenguang Liu.


Advanced Functional Materials,31:4,2006944(2020)