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Development and characterization of disulfide-based self-healing sealants for concrete pavement joints
Date
2025
Authors
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Publisher
University of Delaware
Abstract
Many highways and bridges built decades ago are now reaching the end of their service life, making advancements in material performance increasingly important. Self-healing materials have the potential to autonomously repair damage, thereby enhancing material durability. The development of self-healing polymers so far has been primarily focused on strategies to achieve self-healing, with less attention given to the application-related aspects of these materials. However, without specific material performance requirements, it is challenging to identify future steps for improving the design of self-healing polymers. This study explores the potential of using self-healing sealants for joints in concrete pavements. The sealant incorporates a thiol-epoxy system, with tertiary amines as initiators of the polymerization reaction. The base of the sealant is a liquid polysulfide (Thiokol). The polysulfide component, rich in disulfide bonds, is theoretically capable of undergoing exchange reactions to enable self-healing. The effects of cross-linking, thiol-epoxy stoichiometry, and initiator type were investigated to establish correlations between polymer structure, polymer properties, and self-healing capabilities. This analysis also served as a parametric study where the aim was to determine which formulation best satisfies the specific application requirements. The study addresses uncertainties related to the functionality of commercially available thiols and the interference of epoxy homopolymerization with the thiol-epoxy addition mechanism, particularly in the presence of nucleophilic tertiary amines. Self-healing behavior was characterized by performing tensile testing experiments to quantify the recovery of strength and elongation after self-healing under ambient conditions. In addition, stress-relaxation experiments at different temperatures were carried out to understand the mechanisms driving self-healing. To determine the potential of using triethylamine as a catalyst for disulfide exchange at room temperature, a model reaction between low molecular weight disulfides was examined. The performance aspects of self-healing polymers were evaluated, emphasizing key metrics such as mechanical properties, adhesion to concrete, the impact of mechanical forces on healing efficiency, and resistance to environmental degradation. Findings from this study contribute to the implementation of autonomous self-healing polymers with dynamic disulfide bonds in construction plastics to increase their service life and reduce environmental impact.
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Keywords
Self-healing sealants, Homopolymerization, Concrete pavements, Self-healing polymers, Sealants, Polymer networks