Self-healing corrosion protection film for marine environment

Kim, Heejin,Yarin, Alexander L.,Lee, Min Wook Elsevier 2020 Composites Part B, Engineering Vol.182 No.-

<P><B>Abstract</B></P> <P>This work aims corrosion protection of large marine structures in saline water under realistic conditions of surrounding waves. Self-healing films of Bromobutyl Rubber (BIIR) would normally provide a relatively slow healing, whereas here the additional layer of BIIR with embedded carbon nanotubes (CNTs) used as a heater facilitates self-healing at a much faster rate, which comprises the main unifying topic of this work and is practically relevant. Self-healing BIIR film as the top layer and the attached heater film (CNT/BIIR) as the bottom layer can be prepared by drop casting, painting or spraying of BIIR solution. Joule heating of the CNT/BIIR layer helps to heat the cut site in the BIIR layer up and heal it quickly. BIIR is also a waterproof material and it reveals a successful recovery of a razor-cut crack within a few hours even underwater. CNT/BIIR bilayer coating also passed a corrosion test in saline water and revealed durability being subjected to waves generated by an impeller. Due to these advantages, the proposed method is suitable for corrosion protection of large marine structures.</P>

Ultra-fast bull's eye-like self-healing using CNT heater

Kim, Heejin,Yarin, Alexander L.,Lee, Min Wook Butterworth Scientific Ltd. etc. 2019 Polymer Vol.180 No.-

<P><B>Abstract</B></P> <P>In the present work, carbon nanotubes (CNTs) are dispersed in the polydimethylsiloxane (PDMS) matrix and used as an embedded heating source. The electrically conductive CNT layer provides the Joule heating of the released healing materials into cracks. This accelerates the release and polymerization (self-healing) rates. It is demonstrated that with this modification the healing process, which originally required at least 24 h, is shortened to only 10 min. In addition, it is proved that this approach works very well even in the low-temperature environment, where otherwise, the healing efficiency is low because of the high viscosity of the healing agents and reduced rate of the polymerization reaction. The bull's eye-like geometry proposed in this work can be replicated to protect large areas.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The healing time is reduced remarkably from 24 h to 10 min with an improved toughness. </LI> <LI> This approach works very well even in the ice water bath (T~1 °C). </LI> <LI> The bull's eye-like unit geometry is replicable to protect large areas. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Dynamic Electrowetting-on-Dielectric (DEWOD) on Unstretched and Stretched Teflon

Lee, Min Wook,Latthe, Sanjay S.,Yarin, Alexander L.,Yoon, Sam S. American Chemical Society 2013 Langmuir Vol.29 No.25

<P>Dynamic electrowetting-on-dielectric (DEWOD) of the unstretched and stretched Teflon is reported in the experiments with water drop impact and rebound. We explore experimentally and theoretically the situation with the capacitance different from the standard static electrowetting. Deionized water drops impact onto either an unstretched hydrophobic Teflon surface or Teflon stretched up to 250% strain normally to the impact direction. The surface roughness of the unstretched Teflon increased after stretching from 209.9 to 245.6 nm resulting in the increase in the equilibrium water contact angle from 96 ± 4° to 147 ± 5°, respectively. The electric arrangement used in the drop impact experiments on DEWOD results in a dramatically reduced capacitance and requires a much higher voltage to observe EW in comparison with the standard static case of a drop deposited on a dielectric layer and attached to an electrode. In the dynamic situation we found that as the EW sets in it can greatly reduce the superhydrophobicity of the unstretched and stretched Teflon. At 0 kV, the water drop rebound height (<I>h</I><SUB>max</SUB>) is higher for the stretched Teflon (<I>h</I><SUB>max</SUB> ≈ 5.13 mm) and lower for the unstretched Teflon (<I>h</I><SUB>max</SUB> ≈ 4.16 mm). The EW response of unstretched Teflon is weaker than that of the stretched one. At the voltage of 3 kV, the water drop sticks to the stretched Teflon without rebound, whereas water drops still partially rebound (<I>h</I><SUB>max</SUB> ≈ 2.8 mm) after a comparable impact onto the unstretched Teflon. We found a sharp dynamic EW response for the stretched Teflon. The contact angle of deionized water ranged from 147 ± 5° (superhydrophobic) to 67 ± 5° (partially hydrophilic) by applying external voltage of 0 and 3 kV, respectively. Dynamic electrowetting introduced in this work for the first time can be used to control spray cooling, painting, and coating and for drop transport in microfluidics.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/langd5/2013/langd5.2013.29.issue-25/la401669w/production/images/medium/la-2013-01669w_0014.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/la401669w'>ACS Electronic Supporting Info</A></P>

Solution-Blown Core–Shell Self-Healing Nano- and Microfibers

Lee, Min Wook,Yoon, Sam S.,Yarin, Alexander L. American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.7

<P>Self-healing microfibers with core shell geometry were studied. A commercial binary epoxy was encased in solution-blown polymer nano-/microfibers in the 0.2-2.6 mu m diameter range. The core shell microfibers were formed by coaxial nozzles, which encapsulated the epoxy resin and its hardener in separate cores. Solution blowing, the fiber-forming process used in this work, was at least 30 times faster than the electrospinning method used previously and has already been scaled up to the industrial level. These core shell microfibers show self-healing capability, in which epoxy and hardener are released from the cores of damaged fibers, resulting in polymerization. The epoxy used had a higher strength and shorter solidification time than poly(dimethylsiloxane) (PDMS) used previously. Also, the larger fiber diameters in the present study facilitated faster release of the epoxy resin and its hardener from the fiber cores, shortening the solidification time in comparison to the previous studies. Blister tests were conducted, which measured the adhesion energy of microfiber mats to substrates and the cohesion energy between layers of microfiber mats before and after fatigue damage followed by self-healing.</P>

A review on corrosion-protective extrinsic self-healing: Comparison of microcapsule-based systems and those based on core-shell vascular networks

An, Seongpil,Lee, Min Wook,Yarin, Alexander L.,Yoon, Sam S. Elsevier 2018 Chemical Engineering Journal Vol.344 No.-

<P><B>Abstract</B></P> <P>Corrosion is a natural phenomenon which significantly deteriorates metal properties. The existing corrosion protection methods are costly and require a regular replacement of sacrificial metals or inevitable use of toxic chemicals. So far, various extrinsic self-healing approaches have been attempted to prevent metal corrosion, which have facilitated the corrosion protection at a reasonable cost and non-toxicity level. Here, we review the existing and the recent novel corrosion-protective extrinsic self-healing technologies, focusing on the capsule-based and the fiber-based self-healing approaches, while looking at the pros and cons of these methods. In addition, by introducing potential ways, this review aims to provide insights for the further development of extrinsic self-healing technologies.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An overview of the corrosion protection in extrinsic self-healing materials. </LI> <LI> The existing and recent corrosion-protection self-healing techniques are reviewed. </LI> <LI> Various fabrication methods of microcapsules and hollow fibers are discussed. </LI> <LI> Directions for the further improvements are highlighted. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Heat Transfer of Two-Phase Flow in a Heated Capillary

Y. P. Peles,L. P. Yarin,G. Hetsroni 대한기계학회 1998 Heat transter conference Vol.2 No.1

Advances in self-healing materials based on vascular networks with mechanical self-repair characteristics

Lee, Min Wook,An, Seongpil,Yoon, Sam S.,Yarin, Alexander L. Elsevier 2018 Advances in colloid and interface science Vol.252 No.-

<P><B>Abstract</B></P> <P>Here, we review the state-of-the-art in the field of engineered self-healing materials. These materials mimic the functionalities of various natural materials found in the human body (e.g., the healing of skin and bones by the vascular system). The fabrication methods used to produce these “vascular-system-like” engineered self-healing materials, such as electrospinning (including co-electrospinning and emulsion spinning) and solution blowing (including coaxial solution blowing and emulsion blowing) are discussed in detail. Further, a few other approaches involving the use of hollow fibers are also described. In addition, various currently used healing materials/agents, such as dicyclopentadiene and Grubbs' catalyst, poly(dimethyl siloxane), and bisphenol-A-based epoxy, are described. We also review the characterization methods employed to verify the physical and chemical aspects of self-healing, that is, the methods used to confirm that the healing agent has been released and that it has resulted in healing, as well as the morphological changes induced in the damaged material by the healing agent. These characterization methods include different visualization and spectroscopy techniques and thermal analysis methods. Special attention is paid to the characterization of the mechanical consequences of self-healing. The effects of self-healing on the mechanical properties such as stiffness and adhesion of the damaged material are evaluated using the tensile test, double cantilever beam test, plane strip test, bending test, and adhesion test (e.g., blister test). Finally, the future direction of the development of these systems is discussed.</P> <P><B>Highlights</B></P> <P> <UL> <LI> An overview of the mechanical property recovery in self-healing engineering materials of vascular type is given. </LI> <LI> Novel up-to-date approaches to fabrication of engineering self-healing materials are described. </LI> <LI> The physical and chemical healing mechanisms including chemical reactions are considered and characterized in detail. </LI> <LI> The self-healing manifestations in the restoration of mechanical and anti-corrosive properties are discussed. </LI> <LI> The scale-up industrial perspectives of self-healing nanofibers are highlighted. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Simplified method for estimating the effect of a hydrogen explosion on a nearby pipeline

Bang, B.,Park, H.S.,Kim, J.H.,Al-Deyab, S.S.,Yarin, A.L.,Yoon, S.S. Butterworths 2016 Journal of loss prevention in the process industri Vol.40 No.-

<P>To predict the effect of hydrogen gas tank explosions on nearby pipelines, we first evaluate the increase in air pressure and velocity on a pipeline after a strong explosion. Then, we calculate the bending of an initially straight pipe. We investigate the bending amplitude for various exploded masses of hydrogen, distances measured from the explosion center to the pipeline, and thicknesses of steel pipeline walls. The proposed analytic approach provides a conservative estimate of the worst-case accident scenario involving an instantaneous explosion of a large hydrogen mass leading to the formation of a shock wave. The results may be useful for plant engineers to evaluate the risks associated with pipelines under the presumed explosion scenario of not only hydrogen, but also any other fuel types. (C) 2015 Elsevier Ltd. All rights reserved.</P>

Multiplicity and Stability of Steady Convective Flows in Laterally Heated Cavities

Alexander Yu. Gelfgat,Pinhas Z. Bar Yoseph,Alexander L. Yarin 대한기계학회 1998 Heat transter conference Vol.3 No.1

Hybrid self-healing matrix using core-shell nanofibers and capsuleless microdroplets.

Lee, Min Wook,An, Seongpil,Lee, Changmin,Liou, Minho,Yarin, Alexander L,Yoon, Sam S American Chemical Society 2014 ACS APPLIED MATERIALS & INTERFACES Vol.6 No.13

<P>In this work, we developed novel self-healing anticorrosive hierarchical coatings that consist of several components. Namely, as a skeleton we prepared a core-shell nanofiber mat electrospun from emulsions of cure material (dimethyl methylhydrogen siloxane) in a poly(acrylonitrile) (PAN) solution in dimethylformamide. In these nanofibers, cure is in the core, while PAN is in the shell. The skeleton deposited on a protected surface is encased in an epoxy-based matrix, which contains emulsified liquid droplets of dimethylvinyl-terminated dimethylsiloxane resin monomer. When such hierarchical coatings are damaged, cure is released from the nanofiber cores and the resin monomer, released from the damaged matrix, is polymerized in the presence of cure. This polymerization and solidification process takes about 1-2 days and eventually heals the damaged material when solid poly(dimethylsiloxane) resin is formed. The self-healing effect was demonstrated using an electrochemical analogue of the scanning vibrating electrode technique. Damaged samples were left for 2 days. After that, the electric current through a damaged coating was found to be negligibly small for the samples with self-healing properties. On the other hand, for the samples without self-healing properties, the electric current was significant.</P>