Coaxial Electrospinning of Self-Healing Coatings (original) (raw)
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6th International Conference on Materials Engineering & Metallurgy, (iMat 2017), 2017
In the present study, the preparation of microencapsulated epoxy and it's curing agent and evaluation of this two-component repair system for producing self-healing epoxy coating, with the objective of improving healing efficiency is reported. Epoxy contained microcapsules were prepared by in situ polymerization of urea–formaldehyde resin to form shell over epoxy resin droplets. Chemically and thermally stable nano-porous containers have been synthesized to store DETA as a reactive agent for self-healing epoxy based coatings. The optimal process parameters for synthesizing the micro/nano capsules were selected. The microcapsules were incorporated into the paint formulations just before application. The filled epoxy coatings were prepared by uniformly mixing of the microcapsules together with the mixture of EPON 828 and DETA. When cracks were initiated or propagated in the coating, the neighbor microencapsulated epoxy and DETA would be damaged and released. As a result, repair of the cracked sites is completed through curing of the released epoxy. Micro/nano capsules and final coatings were characterized. All the obtained results show that the prepared self-healing coatings could be suitable for using in different applications.
Sunlight-Induced Self-Healing of a Microcapsule-Type Protective Coating
ACS Applied Materials & Interfaces, 2013
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.
Advanced micro/nanocapsules for self-healing smart anticorrosion coatings
J. Mater. Chem. A, 2014
Smart self-healing coatings for corrosion protection of metallic substrates (steel, magnesium, and aluminium, and their alloys) have attracted tremendous interest due to their capability to prevent crack propagation in the protective coatings by releasing active agents from micro/nanocapsules, that is, micro/nano particles consisting of a coating layer or a shell (micro/nanocontainers) and core material (solids, droplets of liquids or gases), in a controllable manner. This paper aims to give a concise review on the most recent advances in preparing micro/nanocapsules based on different types of micro/ nanocontainers, i.e., organic polymer coatings, inorganic clays, mesoporous silica nanoparticles, polyelectrolyte multilayers, etc. for smart coatings with self-healing properties. The state-of-the-art design and preparation of micro/nanocapsules are highlighted with detailed examples.
A Multiple-Action Self-Healing Coating
Frontiers in Materials, 2016
This article describes a self-healing coating for corrosion protection of metals, which combines two different types of self-healing mechanisms in one coating with multiple-healing functionality. 2-Mercaptobenzothiazole (MBT) was loaded into layered double hydroxide (LDH) carriers that were mixed into an acrylated polycaprolactone polyurethane-based shape-recovery coating and applied on hot-dip galvanized steel (HDG). The effect of triggered release of MBT on the protection of HDG became visible when samples with manually applied defects in the coating were immersed in 0.05 M NaCl solution (first, autonomous-healing mechanism). The shape recovery (second, non-autonomous-healing mechanism) was triggered by heating the samples for 2 min to 60°C. SEM-EDX and Raman spectroscopy proved the presence of MBT in the LDH, in the MBT-loaded LDH in the coating and the released MBT on the HDG surface in the damaged area after being in contact with a solution containing corrosive ions. Electrochemical impedance spectroscopy and scanning vibrating electrode technique demonstrate the corrosion protection effect of MBT in the coating with a defect and the restoration of the barrier properties of the coating after defect closure. This way, the independent mechanisms of this multi-action self-healing coating could be demonstrated.
Bioinspired, Biomimetic and Nanobiomaterials, 2012
Designing of novel self-healing materials possessing an active feedback on various destructive factors is one of most quickly developing areas in contemporary material engineering. Self-healing and self-protecting coatings represent one of particular classes of these materials that able on damage to recover their anticorrosive or antifouling function. Most established approach to impart to the coating this ability is nowadays the use of container-based structures when the protective agent trapped in containers is embedded in the coating matrix. There are different ways to produce containers for the further incorporation into coating but the role of emulsion route in the containers preparation is probably predominant. Herein, the contemporary achievements in the fi eld of emulsion encapsulation are reviewed. Several types of containers for biomimetic functional coatings synthesized via emulsion as an initial system are presented based mainly on the earlier published and very recently obtained results of our research group. An overview is given of some interfacial physical and chemical methods utilized for the transformation of emulsion droplets into nano-or microscaled containers showing their specifi c advantages and drawbacks. Successful incorporation of containers in the diverse types of coatings showed is promising for novel materials production in many application fi elds. 1 2 3 4 5 Pages 101-116 http://dx.
Corrosion-resistant self-healing coatings
AIP Conference Proceedings, 2018
The use of polymeric coatings with self-healing ability is a viable approach for a new smart corrosion protection strategy. Polymer systems are usually applied on a metal surface to provide an effective barrier against the corrosive species. The protective coatings have to delay the inexorable water uptake, blister or crack formation and delamination. Among self-repairing polymers, in this area of interest, Diels-Alder epoxy resins are particularly appealing for coating application, because the products and intermediates obtained during the healing treatment are stable to aggressive environments, such as the major oxidation agents, air and water. In addition, the chemical stability and crosslinked structure of epoxies are preserved and ensure the coating functionality. An intrinsic mendable epoxy system, containing bifunctional adducts, has been prepared by Diels-Alder reaction. Optical microscopy and nanoindention tests validated the morphological and structural recovery of the coating. Immersion test in saline solution revealed the complete restoration of the corrosion protection for a healed sample.The use of polymeric coatings with self-healing ability is a viable approach for a new smart corrosion protection strategy. Polymer systems are usually applied on a metal surface to provide an effective barrier against the corrosive species. The protective coatings have to delay the inexorable water uptake, blister or crack formation and delamination. Among self-repairing polymers, in this area of interest, Diels-Alder epoxy resins are particularly appealing for coating application, because the products and intermediates obtained during the healing treatment are stable to aggressive environments, such as the major oxidation agents, air and water. In addition, the chemical stability and crosslinked structure of epoxies are preserved and ensure the coating functionality. An intrinsic mendable epoxy system, containing bifunctional adducts, has been prepared by Diels-Alder reaction. Optical microscopy and nanoindention tests validated the morphological and structural recovery of the coating. Immersion test in...
The influence of size and healing content on the performance of extrinsic self‐healing coatings
Journal of Applied Polymer Science, 2020
Among the several approaches for the protection of metallic structures from corrosion, covering with a polymeric coating has attracted more attention due to their convenient application, cost-effective price, and the relatively benign environmental impact. However, the polymeric coatings are sensitive to mechanical/thermal shocks and aggressive environments, leading to damages in the coatings that affect their barrier performance. Self-healing polymeric coatings have introduced remarkable development by extending the service life and reducing maintenance costs, leading to a significant boost in the reliability and durability of the conventional polymeric coatings. Among the different strategies to develop self-polymeric coatings, encapsulating healing agent within micro/nanocapsules, micro/nanofibers, and microvascular systems and incorporating them within the conventional coatings have been widely acknowledged as the most applicable approach. However, several factors, such as the effect of the healing system's size and content, have a significant influence on healing performance. Therefore, this review aims to reveal the effects of healing system size and healing content on the self-healing performance in polymeric coatings through the analysis of recently published articles. K E Y W O R D S coatings, surfaces and interfaces, resins 1 | INTRODUCTION In most industries, metals are utilized due to their superior physical and mechanical properties. However, metal structures are usually affected by corrosion, wear, and erosion, which cause high financial damages. According to the World Corrosion Organization (WCO), the global annual cost of corrosion is approximately 3.1%-3.5% of a country's gross domestic product (GDP). 1 The situation is more critical when the metallic structures are used as
Applications of Microcapsules in Self-Healing Polymeric Materials
Microencapsulation - Processes, Technologies and Industrial Applications [Working Title]
Self-healing polymeric materials have a great potential to be explored and utilized in many applications such as engineering and surface coating. Various smart materials with self-healing ability and unique self-healing mechanisms have been reported in recent publications. Currently, the most widely employed technique is by embedding microcapsules that contain a healing agent into the bulk polymer matrix. When cracks develop in the polymer matrix, the curing agent is released from the microcapsules to cross-link and repair the cracks. Microencapsulation of the healing agent in the core can be achieved by in situ polymerizing of shell material. This chapter presents a general review on self-healing materials, and particularly, self-healing of epoxy matrices that includes epoxy composite and epoxy coating by microencapsulation technique. Microencapsulation processes, including types of resin used, processing parameters such as core/shell ratio, concentration of emulsifiers, viscosities of aqueous and organic phases and stirring rate are discussed.
Self-healing coatings in anti-corrosion applications
Journal of Materials Science, 2013
Nonmetallic (based on polymers or oxides) and metallic protective coatings are used to protect metal products against the harmful action of the corrosion environment. In recent years, self-healing coatings have been the subject of increasing interest. The ability of such coatings to self-repair local damage caused by external factors is a major factor contributing to their attractiveness. Polymer layers, silica-organic layers, conversion layers, metallic layers and ceramic layers, to mention but a few, are used as self-healing coatings. This paper presents the main kinds of self-healing coatings and explains their selfhealing mechanisms.