Encapsulation of solvent into halloysite nanotubes to promote self-healing ability in polymers

Abstract

Microcracking during service is a critical problem, which can be particularly detrimental to the durability of polymers and polymer composite structures. Materials with self-healing ability are capable to partially or completely repair damages, thus increasing the life of the structural component. One of the self-healing approaches involves the use of solvents as healing agent, which reacts with the polymer healing microcracks. The objective of this research is to investigate a procedure to encapsulate solvents into halloysite nanotubes (HNT) to promote self-healing ability in epoxy. Autonomic healing would be triggered by crack propagation through the embedded nanotubes in the polymer, releasing the liquid solvent into the crack plane. Two solvents were considered in this work: dimethylsulfoxide (DMSO) and nitrobenzene. A procedure was developed to fill HNT with the solvents, which were then coated using the layer-by-layer technique of oppositely charged polyelectrolytes. Solvent encapsulation was verified by X-ray diffraction, Fourier transform infrared analysis, thermogravimetry, specific surface area (BET), and scanning electron microscopy. The results suggest that the procedure was successful to encapsulate DMSO into the nanotubes.

Keywords:

• self-healing materials
• composite materials
• nanotubes
• halloysite