Sunlight-Induced Self-Healing of a Microcapsule-Type Protective Coating

Abstract

Photopolymerization behavior of a methacryloxypropyl-terminated polydimethylsiloxane (MAT-PDMS) healing agent was investigated in the presence of benzoin isobutyl ether (BIE) photoinitiator by Fourier transform infrared (FT-IR) spectroscopy. MAT-PDMS and BIE were microencapsulated with urea-formaldehyde polymer. The surface and shell morphology of the microcapsules was investigated by scanning electron microscopy (SEM). Mean diameter and size distribution of the microcapsules could be controlled by agitation rate. A coating matrix formulation was prepared by sol-gel reaction of tetraethyl orthosilicate (TEOS) in the presence of a polysiloxane and by subsequent addition of an adhesion promoter. The formulation and microcapsules were mixed to give a self-healing coating formulation, which was then sprayed to surface of cellulose-fiber-reinforced-cement (CRC) board or mortar. Contact angle measurements showed that both the polymerized MAT-PDMS and the prepared coating matrix are hydrophobic, and the coating matrix has good wettability with MAT-PDMS. It was confirmed by optical microscopy and SEM that, when the self-healing coating is damaged, the healing agent is released from ruptured microcapsules and fills the damaged region. The self-healing coating was evaluated as protective coating for mortar, and it was demonstrated by water permeability and chloride ion penetration tests that our system has sunlight-induced self-healing capability. Our self-healing coating is the first example of capsule-type photoinduced self-healing system, and offers the advantages of catalyst-free, environmentally friendly, inexpensive, practical healing.

The methodologies and strategies for the development of novel material systems and coatings for applications in extreme environments − a critical review

“…The formulation and microcapsules were then mixed, resulting in a self-healing coatingformulation. A use involved spraying of the coatingformulation onto the surface of a board made of cellulosefiber-reinforced-cement and a motar [52]. It was revealed that the healing agent could be released from the ruptured microcapsules and then filled the are where the damage occured, and a sunlight-induced self-healing capability was also demonstrated during the tests on the motar.…”

Research on Preparation and Properties of Coated Polyether Silicone Microencapsulation Based on Polystyrene

“…Verify capsule core structure: weigh a small amount of silicone polyether microcapsule samples to two sheets of a piece of clean glass, provide the existence of oily phase in the sample microcapsule by squeezing and observe the oil phase overflowing [7] .…”

A Study on the Manufacturing Properties of Crack Self-Healing Capsules Using Cement Powder for Addition to Cement Composites

“…In one international study, self-healing materials and catalysts were encapsulated as microsized capsules [5,6]. Meanwhile, in Korea, selfhealing microsized capsules capable of reacting with sunlight or moisture without catalysts have been applied in actual construction [7]. Two conclusions can be derived from these case studies at home and abroad.…”