Recently LG announced its new smartphone, G-Flex, which is curved, flexible (one can literally sit on it), and has a self-healing polymer coating on the back: Light scratches disappear before your eyes. While an observant customer can connect the flexible smartphone screen to the flexible OLED on LG’s website, the nature of proprietary self-healing coating remains a mystery.
Lauren Davidson at Quartz hypothesized about the possible mechanisms based on recent polymer self-healing achievements:
- hydrophobic self-replenishing surfaces using caprolactone polymer networks with spontaneous reorientation of surface fluoroalkyl groups
- self-healing bioplastics, designed after the Brazilian rubber tree, that have adhesive-loaded microcapsules mixed in synthetic caoutchouc
- spontaneous self-healing polymer using re-forming disulphide bonds
- self-healing synthetic skin using re-forming hydrogen bonds in touch-sensitive, (i.e., conductive) nickel microparticle-containing polymer
Interestingly, the concept of self-healing is not limited to polymers. Self-healing electronics can be designed using the “classic” self-healing approach, with microcapsules rupturing upon injury and delivering a mending agent, which in the case of electronics is liquid metal. And finally, there is spontaneous crack-healing in metals discovered at MIT last month, which is related to an interesting phenomenon of disclination (previously “dis-inclination”), originally described for liquid crystals. Disclination is a line defect or, more precisely, a boundary between areas with different symmetries, like crystal grain areas; these defects can appear and disappear (i.e., heal) in both living and non-living systems (see video).
The World Economic Forum named self-healing materials (along with 3D printing, organic electronics and photovoltaics) among the top 10 emerging technologies for 2013 “that can help to deliver sustainable growth in decades to come as global population and material demands on the environment continue to grow rapidly.”
This is how the Global Agenda Council on Emerging Technologies describes self-healing materials:
One of the defining characteristics of living organisms is their inherent ability to repair physical damage. A growing trend in biomimicry is the creation of non-living structural materials that also have the capacity to heal themselves when cut, torn, or cracked. Self-healing materials which can repair damage without external human intervention could give manufactured goods longer lifetimes and reduce the demand for raw materials, as well as improving the inherent safety of materials used in construction or to form the bodies of aircraft.
It’s exciting to see that the self-healing phenomena is becoming a trend in material science.
Source: OLED materials, lgchem.com
Source: Here’s how LG’s self-healing G Flex smartphone could work, Lauren Davidson, qz.com, October 29, 2013
Source: Self-Replenishing Surfaces, T. Diki, W. Ming, R. A. T. M. van Benthem, A. C. C. Esteves, G. de With, Advanced Materials, Volume 24, Issue 27, pages 3701–3704, July 17, 2012, DOI: 10.1002/adma.201200807
Source: Scientists Developing Self-Healing Plastics Inspired by Rubber Tree Plants by Jessica Dailey, inhabitat.com, March 9, 2011
Source: Self-healing electronics could work longer and reduce waste, news.illinois.edu
Source: Cracked metal, heal thyself, David L. Chandler, MIT News Office, web.mit.edu, October 8, 2013
Source: Spontaneous motion in hierarchically assembled active matter, Tim Sanchez, Daniel T. N. Chen, Zvonimir Dogic, Nature 491 (7424): 431-434, November 15, 2012
Source: Hydrophobic modified polyrotaxane and crosslinked polyrotaxane, United States Patent 7943718, www.freepatentsonline.com
Source: Nissan develops self-repairing paint, Mike Hanlon, gizmag.com, December 2, 2005
Source: Nissan introduces self-repairing iPhone case, Tyler Lee, ubergizmo.com, January 16, 2012
Source: Active Nematic Liquid Crystal, DogicLab, youtube.com
Source: The top 10 emerging technologies for 2013, David King, World Economic Forum, forumblog.org, Source: The top 10 emerging technologies for 2013, David King, World Economic Forum, forumblog.org; February 14, 2013
Video: LG G Flex Self Healing Demo! Marques Brownlee, youtube.com
Video LG G Flex – Self Healing and Durability, youtube.com
Image by LGEPR