The role of self-healing coatings on soft polymer fibers

Abstract

Mussel byssal threads exhibit unique self-healing mechanical properties. This study designed a synthetic system modeled after the byssal thread structure in order to isolate the origins of their unique self-healing mechanical properties. PDMS fibers were coated with metal-coordination bonds crosslinked PEG gels and their mechanical properties were tested with uniaxial tension tests. The synthetic system achieved a similar behavior to that of the natural mussel fibers, showing that a thin stiff coating on a soft polymer fiber can have a dramatic effect on its mechanical behavior. The coated fibers were much stiffer at small strains than the uncoated PDMS. The linear elastic region was followed by a distinct yield stress, which indicated the coating beginning to fracture. At high strains, when the coating had failed catastrophically, the PDMS behavior dominated. The coatings were healed though hydration in a humid environment and were then able to recover their stiffness similar to mussel byssal threads.