Self-Healable and Reprocessable Polysulfide Sealants Prepared from Liquid Polysulfide Oligomer and Epoxy Resin

Abstract

Polysulfide sealants have been commercially applied in many industrial fields. In this article, we study the self-healing property of the epoxy resin-cured polysulfide sealants for the first time. The obtained sealants showed a flexible range of ultimate elongation of 157-478% and a tensile strength of 1.02-0.75 MPa corresponding to different polysulfide oligomers. By taking advantage of the dynamic reversible exchange of disulfide bonds, polysulfide sealants exhibited good self-healing ability under a moderate thermal stimulus. A higher molecular weight and a lower degree of cross-linking of polysulfide oligomer were helpful in improving the ultimate elongation and healing efficiency of the polysulfide sealants. After subjecting to a temperature of 75 °C for 60 min, both the tensile strength and ultimate elongation of a fully cut sample, LP55-F, were restored to 91% of the original values, without affecting the sealing property. Furthermore, the sample exhibited excellent reshaping and reprocessing abilities. These outcomes offer a paradigm toward sustainable industrial applications of the polysulfide-based sealants.

Fusion of Different Crosslinked Polymers Based on Dynamic Disulfide Exchange

“…Over the last decades, many DCBs have been reported based on for example, imine exchange, transesterification, olefin metathesis, reversible boronic ester formation, and dichalcogenide bond exchange . In addition, various studies on CLPs, including DCBs, have revealed that CLPs that contain DCBs show a variety of functionalities, such as self‐healing, shape memory, reversible sol‐gel reactions, stress relaxation, and reprocessing . Especially self‐healing based on bond‐exchange reactions is expected to prolong the lifetime of materials by preventing fatal structural disintegration.…”

Aromatic amine‐terminated polysulfide oligomer: Synthesis and application in self‐healable polyurea

“…However, the relatively low tensile strength of polysulfide‐based materials is caused by a weak interaction force between polysulfide chains. Our group recently explored the use of aromatic epoxy resin and polyurethane as hard segments to strengthen self‐healable polysulfide‐based materials, resulting in a tensile strength of 0.75 and 2.62 MPa, respectively . Considering practical applications, self‐healable materials with higher tensile strength are often desired .…”

Synthesis and healing properties of poly(arylene ether sulfone)‐poly(alkyl disulfide) multiblock copolymers

“…Disulfide bonds are well‐known dynamic covalent bonds, and self‐healing materials containing these are described in the literature . Yoon et al reported autonomous self‐healing disulfide‐crosslinked star polymer gels .…”

“…Klumperman and coworkers reported epoxy resins containing disulfide bonds which can be healed by heating . Thermal‐induced self‐healing polysulfide thermosets and sealants were also reported . Otsuka and coworkers reported disulfide‐containing dynamic covalent polymers driven by disulfide metathesis reactions by photoirradiation .…”