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.
Over recent years, chemically-induced hibernation has attracted much attention in fields of hibernation biology, medical science and space biology.1,2 Several compounds such as thyronamine and gaseous H 2 S are shown to trigger hibernation-like state (HS) in non-hibernator mice.3,4 For instance, a single-dose administration of thyronamine elicited rapid suppression of metabolic rate, body temperature (T b ) and heart rate, and elevated utilization of lipid over carbohydrate for metabolism in the laboratory mice.3,5 From the perspective of HS induction, 3-iodothyronamine (T 1 AM) has drawn a particular attention because it is an endogenous compound derived from deiodination and decarboxylation of thyroid hormone T 4 (thyroxine). The compound is shown to cause little side effect or damage on neural and other critical organs even for a long-term, repeated administration.3,6a,7 These findings render T 1 AM to have pharmaceutical benefits that can be applied to emergency medical care (e.g., stroke, hypoxic assault), organ transplantation, and a long-duration spaceflight.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.