Self-Healing of a Cross-Linked Polymer with Dynamic
Covalent Linkages at Mild Temperature and Evaluation at Macroscopic
and Molecular Levels
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Abstract
A lot
of self-healing materials using dynamic bonding systems have
been reported, while the focus is mainly on the macroscopic self-healing
behavior such as visually recognizable healing. Because the healing
originates from microscopic chemical reactions of the dynamic bonds,
evaluation of the reactions in the materials is necessary for elucidation
of the healing mechanisms and development of the healing ability.
Herein, we demonstrated self-healing of a cross-linked polymer with
diarylbibenzofuranone (DABBF)-based dynamic covalent linkages at mild
temperature and investigated the healing behavior from both macroscopic
and microscopic viewpoints. The macroscopic behavior was inspected
by mechanical tests, and the linkage reaction (equilibrium) was evaluated
by electron paramagnetic resonance measurements. These assessments
revealed that the healing is strongly dependent on temperature, which
is attributable to synergism between changes in the chain mobility
and in the equilibrium of the incorporated linkages. These findings
would be applicable to other dynamic bonding systems