Effect of mechanical properties on the self‐healing behavior of waterborne polyurethane coatings

Abstract

The effect of structural parameters such as hard segment content and cross-linking degree on the mechanical properties of waterborne self-healing polyurethane and the effect of tensile strength, self-healing conditions (temperature, time) on the selfhealing properties were investigated. These results demonstrated that as the increasing of the content of hard segments/the cross-linking agent, the tensile strength of the sample increased and the self-healing performance exhibited a downward trend. When the tensile strength reached 40 MPa, it could hardly healed, even if prolonging the self-healing time or increasing the self-healing temperature. Mechanism study demonstrated that the self-healing ability was attributed to the dynamic exchange of disulfide bonds and the thermal reversibility of hydrogen bonds in the system. Hydrogen bonding could provide the initial selfhealing force and promote the dynamic exchange reaction of disulfide bonds, while high hydrogen bonding is not conducive to the movement of macromolecular segments, causing a decrease in the self-healing efficiency.

Self-healing polyacrylates based on dynamic disulfide and quadruple hydrogen bonds

“…Therefore, the self-healing efficiency of the PAUS sample was slightly lower than that of PAS and PAU samples. 54,55 From Fig. 6c, the self-healing behavior of the PAUS sample was found to be time-dependent.…”

Study on damping and self‐healing properties of polyurethane materials based on dynamic synergetic control of disulfide bond and imine bond

“…This characteristic has led to significant advancements in the field of self-healing materials. [7][8][9][10] Commonly used dynamic reversible bonds for preparing self-healing materials include covalently adaptive networks(CANs), 10,11 Diels-Alder reactions, 12,13 disulfide bonds, 14,15 imine bonds, 16,17 hydrogen bonds, 18,19 and metal-complex bonds. [20][21][22] Disulfide bonding is a very important reversible chemical bond that is widely found in living organisms and most proteins.…”

Self‐healing and reprocess of crosslinked polyurethane based on dynamic oxime‐carbamate bond

“…However, crosslinking usually sacrifices its reprocessing ability, and even sacrifices its functionality 20 . In our previous works, we investigated the effect of cross‐linking degree and mechanical properties on the self‐healing of disulfide bonds type PU, and found when the mechanical strength of PU film reached above 40 MPa, it was hard to heal even if prolonging the self‐healing time and increasing the self‐heal temperature, crosslinking shows an obvious negative effect on their self‐healing 21 . Therefore, how to develop high performance PU with self‐healing and reprocessing properties has always been a challenge for the academic community.…”