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Self-Healing Material Webinar


hello everyone thank you for joining us
today my name is Chris campen I’ll be your host for this technology gateway
webinar on NASA’s self-healing material our presenters today are dr.
Scott Zavada and dr. Keith Gordon. Scott Zavada is a research engineer with the
National Institute of aerospace and works with the advanced materials and
processing branch at NASA Langley Research Center prior to earning his PhD
in macro molecular science and engineering from the University of
Michigan in 2016 Scott held a bachelor’s degree in
chemistry from Adrienne College in 98 and his master’s in polymer technology
from Eastern Michigan in 09 prior to freely pursuing his doctorate Scott
worked as a senior research chemist from 98 to 2011 at precision coatings Inc
during which time he was awarded patents on dry erasable coatings and laser
ablative photomasks an already accomplished researcher Scott’s ongoing
interest include self healing and stimuli responsive materials bio
chemistry high-temperature polymers and composites organic and inorganic hybrids
and additive manufacturing. Dr. Keith Gordon is a materials research engineer
at NASA langley research center keith earned his bachelor’s degree in
chemistry from Morehouse College in 97 and went on to earn his PhD in polymer
and organic chemistry in O3 from Clark Atlanta University his NASA career
started in 04 in the advanced materials processing branch where he
began research primarily and developing flame retardant materials and proton
exchange membranes for fuel cell applications however in the past 11
years keith has been working in the development of self self-healing
materials where he has preserved as co-principal investigator and team lead
on various projects dr. gordon authored and co-authored 20
scientific publications 5 patents and over 30 technical presentations has been
an awardee of an Editors Choice Award and a group of teaming awards
now before we started I like to point out that your microphones will be muted
throughout this presentation so if you have any questions please type them into
the chat box and we will answer them during the Q&A session at the end so at
this point I’m going to turn it over to you Scott good afternoon everybody thank
you for joining us today we will be talking about a multi-layered soft
healing material system and this material was designed to mitigate
the damage that results from a puncture from a high-velocity projectile
something like a micrometeoroid or orbital debris this material is
constructed by sandwiching a reactive liquid monomer formulation between two
solid Palmer panels and while we designed this material with space
exploration in mind I think that has uses far beyond this initial application
so first I want to give you the background on this project and how we
came about developing it this is research that I performed well a
graduate student at the University of Michigan working under professor Timothy
Scott and during this time I was also a NASA space technology research fellow so
professor Scott at Michigan challenged me to look at different ways of
performing institute polymer formation this is where a liquid monomer is
converted into a solid polymer by exposing this liquid to some stimulus
now this is a pretty common idea in many commercial applications to give you a
few common examples superglue is a liquid while it’s kept within its
container and after it’s squeezed out and released into the environment it
reacts with humidity that is natural presidents that is naturally present
that triggers a series of reactions that turns it from a liquid into a solid
adhesive ultraviolet light can be used to convert liquid into a solid so there
are lots of paint films applied as liquid to a material there’s a shine
ultraviolet light on it that’s triggered a series of reactions
turns out liquid paint into a solid protective coating professor Scott at
Michigan challenged me to convert a liquid into a solid by exposing that
liquid oxygen and he challenged me not only to develop different types of
chemistry that were capable of this but also to find potential applications for
it so what application that I considered was how NASA might use this NASA is
interested interested in sending humans back beyond low-earth orbit with suit
revisions planned to the moon and to Mars these extended missions
we’ll rely on the use of these space exploration habitats such as the ones
pictured and illustrated here the habitats will give the astronauts a
place where they can live work and sleep safely but there are serious concerns
about the vulnerability of these habitats in particular what happens if
the habitat wall is punctured well say a micrometeoroid hits the hits the habitat
punctures a hole through the wall this creates a hole that allows the
atmosphere to rush out draining the oxygen from the structure and putting
the lives of those inside at risk so NASA was interested in developing
materials that if they are punctured they automatically seals that seal
themselves up closing that reach and preventing further loss of atmosphere
but somewhat impressively nASA has developed some plastics that have this
property under certain circumstances one of them is called Serling this is a
commercially available polymer some grades are best known for their use
commercially as the outer covering of a golf ball there’s also a polymer called
PBG of a chemical name here shown at the bottom so under certain certain
circumstances if these materials are punctured by a high-velocity projectile
the hole will seal off with those limitations server it will only work at
a lower temperature range PBG will only work at a higher temperature range and
there’s some gaps in between well it won’t necessarily work so I thought I
might be able to improve on the system to add another mechanism for healing to
reinforce the the natural properties of these two types of plastic so my idea
was to incorporate this reactive liquid monomer layer in between two solid
polymer layers and these pop solid polymer layers could be materials like
sirloin or PBG so now if this were punctured by projectile like a
micrometeoroid as the air starts to rush out this reactive liquid monomer will
seep into that hole come in contact with the atmosphere rushing out this
atmosphere contains oxygen I will then use the oxygen to initiate a
polymerization reaction to convert that reactive liquid monomer
into a solid polymer plug this will seal that breach and prevent loss of
atmosphere so in order to put this idea into
practice I had to figure out ways first of how do I turn a liquid into a solid
banks was in that liquid oxygen and found I did this in a two-step process
one I would use oxygen to generate radicals radicals are very reactive
chemical species that are often used to initiate these types of polymerization
reactions and then I would be so I would use these radicals made first by this
reaction with oxygen and second I would use that to start this additional
reaction that would convert the liquid into a solid so for the first first item
here to convert oxygen into radicals I use the class of compounds known as
trialkyl borings these chemical species in the presence of oxygen will form
several types of radicals the actual VV some actual examples of tri alkyl
borings two common ones are tributyl boring and tri alpha boring the one that
i used in my experiments primarily was tributyl boring for the polymerization
reaction I relied on what is known as the style in reaction this is a reaction
between a sigh off which is an SH and in Ian this is a double bond containing
species it includes things like vinyls vinyl ethers alleles or allele users
when these two species chemical species are present in the presence of radicals
they will react together to form a style ether linkage if we use monomers that
have multiple functional groups so for example here’s an here is a a dice I off
with its 2008 rile either these materials are combined in the presence
of radicals it will live arise and form a solid polymer so initially I did a
considerable amount of research at my lab at the University of Michigan and it
summarized the main points of what I found out there we found that or
relations of a style and an E monomer along with the tribunal boring would be
a liquid in the absence of oxygen if over one percent tributyl boring was
present in the formulation it was solidified rapidly when exposed to air
and we found that by adjusting the types of monomers used and the tributyl boring
concentration we get it has occasion happening within seconds of
being exposed to the atmosphere so having developed us these reactive
formulations we wanted to actually test it to actually put it into a panel and
puncture it and see what would happen and we did that work here at the NASA
Langley Research Center so we constructed test panels they have this
reactive liquid monitor between two solid polymer panels to simulate
micrometeoroids puncture we fire bullets at it to do bullet with ballistics
testing and we monitor the results using various types of high speed video
cameras the actions give you the specifics on the ballistic testing we
took a three by three inch panel set that in a test and 11 meters from a
rifle we have a luckily were to have a NASA sharpshooter president here at NASA
Langley Romans from the rifle fire two to three caliber Full Metal Jacket
bullets we use this type of ammunition as attempts to punch a clean hole to raw
material and we thought this would best simulate micrometeoroids bump sure we
set up high-speed video cameras that would allow us at a to collect data at a
hundred thousand frames a second to show what would happen as the bullet
approached contacted penetrated through and then passed on
the test panel well to show you some of the results of the step thing here is a
control experiment that we did this has the two solid polymer panels on the
front and back with a liquid formulation in the middle that does not contain
tributyl boring so it does not contain the initiator that actually can react
with oxygen to start the series of polymerization reactions that would turn
the liquid into a solid this will we expect it and it did just remain a
liquid one does use this as a point of comparison so as I play the video you’ll
see the bullet passed through the material and very quickly you see the
screen will liquid consuming out this is entirely as we expected because this
material is unreactive showing a video that we took afterwards you receive me
squeezing the sample and look what just oozes out again this is exactly as we
expected because it’s liquid it’s not capable of
they compare that now to the video that we took of us of a sample where we did
include 2% tributyl boring so this has the initiator this is capable of
reacting with oxygen so the bullet passes through unlike before we don’t
see much happen afterwards if we look at a video that was collected after that
task you see me squeezing the sample around the edges away from the impact
site you still see the bubbles move so it’s cool a liquid there but at the site
of penetration that liquid had turned into a solid and is able to test that
with a vacuum line early on and it did completely seal up that hole so that was
very exciting this seemed to prove though the basic feasibility of this
idea we published as a result in an ACS macro letters published by the American
Chemical Society it was selected as an editor’s choice article by the ACS
meaning if you are interested in reading this this is freely available for
downloading for free to everybody the American Chemical Society put out a
press release on this really on this research that got a tremendous amount of
press there’s numerous articles that appeared throughout popular media my
advisor was interviewed on Scientific American 60-second science podcast and I
was interviewed on Michigan Public Radio many of these articles were quite well
well written and explained the research accurately others exaggerated a bit and
they seem to suggest that this type of technology is much further along than
what it was way that we saw this was this was a very successful first step
but we know that there is much more research that needs to be done to get
this to the point where it could be used in a commercial product while still a
graduate student I had the chance to start working on one of these next steps
so one of the limitations of this test is that both the front and the back side
of the panel are under atmospheric pressure for the applications that we’re
interested in you know meaning these base habitats that would be on the moon
or on Mars there will always be a pressure differential the outside will
be vacuum or near vacuum and the inside will be pressurized so we want to be
able to perform the experiments under a pressure
differential to do that we went to the NASA Glenn Research Center in Cleveland
Ohio and they constructed a pressurized box for me or the sample would sit in
the front side of this box this box was then fit sit inside a larger vacuum
chamber which is connected to a barrel and a pressure vessel we were able to
pump the outer vacuum chamber down to about a tenth of an atmosphere so there
was about a ten to one pressure differential this level vacuum is not as
low as it would be on obviously on the moon or even on Mars but this is a good
simulation at least it’s a good first step beyond what we did in our initial
testing with this experimental setup we’re able to launch a a projectile a
steel ball bearing which is propelled by a plastic what is known as a sub Oh down
this downward gun barrel at 900 meters a second now we don’t want these to bow
slamming into our sample so we put at a the device at the end of the barrel
installed to catch the scible and would only allow the metal steel ball-bearing
to strike z to strike the sample to show you a photo of what the external setup
looks like we see the metal pressurized box which should be pressurized to one
atmosphere the test panel sits in the front of that and the dotted line shows
the projectile path of the steel ball bearing a note to that what this set of
also allowed us to monitor this process with high-speed video cameras so the
samples were constructed as they were before with a reactive liquid monomer
formulation sandwiched between two solid polymer supports now one of the issues
that we had anticipated was that under a pressure differential those low
viscosity liquid might shoot out through this hole before it has a chance to
polymerize so to help mitigate that problem within the liquid we inserted a
glass fiber a glass fiber mesh in the hopes that this mesh would help to grab
on to liquid long enough to allow it to have time to slimmer eyes and solidify
to stay and seal that hole so here’s some videos of the data that we
collected with this with this experimental
process and again this first the first video I will show you is with an
unreactive liquid just for point of comparison so they play the video you’ll
see a cloud of debris and amongst that debris will be the steel ball-bearing
that penetrates the sample and very quickly afterwards we see this liquid
being ejected quite violently much more violently than before owing to the
pressure differentials from the backside of the panel which pressure pressurized
and the near vacuum conditions on the outside this is again much more dramatic
than the the sample that we tested just at atmospheric pressure so compare this
will be formed with these sample formulations that contained 2% regular
boring so again this formulation has the initiator in the monomer and this will
react in contact with oxygen as I play back this video again you’ll see the
cloud of debris and steel ball-bearing it’ll pass through the sample creating a
hole and not a whole lot happens right now if we were to play this video back
long enough you would see a small amount of solid material extruded through this
hole and I went when I went back and examined the sample the hole did not
seal up completely but it was much much smaller than it would have would have
been otherwise because of the complexity of the setup we only had a chance to
test a limited number of samples but even getting this for this far on our
first attempt I thought was very promising so now that was how far I was
able to take this project while a graduate student at the University of
Michigan I think there’s a lot more work that can be done to to improve upon this
I think the first question that needs to look at is the best way of packaging the
liquid within the primary structure what I did was just to sandwich this liquid
within two solids there might be better ways of doing this like including a
honeycomb structure along with the liquid or maybe embedding the liquid
within capsules or some kind of three-dimensional tube you’ll or even
like a vascular type Network I think another question I need to be answered
is how stable are these reactive liquids for the experiments that I performed I
was I would make them up in the morning and the testing throughout the day and
that for my purposes I was able to demonstrate the
feasibility but I never looked at the long-term stability of these reactive
liquids so I never looked at how they would behave a month or a year or two or
three years after that and that is that is a real concern that would have to be
addressed before this to be used in a commercial product there doesent
summarize the summarizes material we have a multi-layered cellular material
system with this reactive monomer layer in the middle that is able to react with
oxygen to form a solid plug that can seal up a breach on either side of this
our plastics that if they are punctured by a high-velocity projectile under
certain temperature ranges they too are also able to heal themselves up to seal
that breach which could in a space habitat prevent loss of atmosphere our
hope is that by including multiple hewing mechanisms within one wall at
least one of these under any type of damage event will be able to seal up
that hole we felt that just using a single healing mechanism was too risky
and it’s too hard to account for all types of damage modes but by having
multiple types of healing we would account for a wider variety of damage so
what we had in up designed this say it was the thought of space exploration in
mind we think this technology has applications to go far beyond that I
think there’s uses throughout aerospace and Aeronautics we also think it could
be useful as a liner in a fuel tank you might be useful in radiation shielding
we think I might have some thrust real applications for use as a wire
insulation material and we furthermore we think it could be utilized in
robotics or things like windows so that I listen turn you over to my colleagues
all right thank you Scott we received a number of questions during the
presentation and will get to them shortly but as Scott said we are going to turn
this over to my colleague as well Kim Middleton she’s going to give a
brief overview of how businesses can partner with NASA through technology
licenses hi I’m Kim Middleton I’m a licensing
specialist here at NASA Langley Research Center and also in the room with me is
Glen King he’s my teammate and also a licensing specialist on this next slide
here you can see some of the businesses that we have done companies that we’ve
done businesses with out in the past and you can see that there’s a large range
of them so let’s get started so here at NASA Langley we mainly focus in the
areas of advanced materials aerospace application sensors and detectors to
find these technologies the best thing to do is go to our website the
technology gateway or NASA tech transfer copy down that website and you can go
there and search for just about any technology you want to you can also
learn about other ways of doing business with us such as SpaceX agreements and
SBIR opportunities we have several licenses here types of licenses at
Langley the first one we’ll discuss is the standard commercial license it’s
available to domestic and international organizations there are exclusive
license which means the field of use is limited just to a specific field abuse
or we only deal exclusively with you the partially exclusive license is one where
where you deal with the particular field of you geographic territory or term so
we can license to another company and maybe a different geographic territory
or maybe who’s using it in a different field of use and then there’s the
non-exclusive license and these terms are negotiated on a case by case basis
we also instituted the start-up license this was developed to help them to
address to the biggest challenges faced by most companies today
startup companies and that’s raising capital and securing IP so we don’t
charge you anything upfront for these licenses but once you start selling it
a product or collecting money we will look at doing their commercial license
and charging either standard 4.2 running royalty these startup licenses are
available to companies formed expressly with the intent of commercializing and
NASA technology they are only available to US companies they are non-exclusive
as I mentioned no upfront cost and there are no minimum fees for the first three
years the next license we have is an evaluation license and it’s kind of
takes the approach try it before you buy it
we will license this to you for our twenty five hundred dollar fee for about
one to two years and it allows you to test and demonstrate the technology
again these are both for non-exclusive licenses so how do you get started well
the first thing you would do would be to submit an application I’ll point out I
think the application is a little hard to find so once you search that website
you find the technology you’re interested in on the right-hand side up
at the top is a little button that says submit your application here along with
that for the commercial license we need a well with all of them we need a
certificate of incorporation for mercial we also need a financial statements a
business and commercialization plans projected revenue and royalties and a
company balance sheet we will then negotiate the terms to get these license
started here’s a little flow chart that just kind of runs through the process
you go to that tech gateway you’d find that technology or this technology that
you think would work well you’ve contact somebody in our office for the specific
technology be myself are on glen keane you would talk to us and we would find
out if it was a fit for your company and what you wanted to do we would decide
what type of license would best be suited for your needs you submit that
application we would review it and after the review
we would decide if you qualify to have the license and then we go into the
negotiation process and come up with the terms of the agreement and develop those
and come to something agreeable to both you and the and NASA was that the greet
upon you excited and there you are you are a licensee of NASA’s technology if
you need any other information here is my contact information on this slide and
there’s also the website for the technology gateway as I mentioned before
that you can go and farm whatever you’re interested in licensing we thank you
very much for listening us today we hope that we can be of help to you and we
hope that this technology that Scott’s presented to you today will be a value
to your company great thank you very much Kim we received a good number of
questions don’t never going to be able to get to all these today but we will
certainly be following up with every question that we do not answer during
this webinar so thank you for everyone who submitted so far again please
continue to type your questions into the chat box we will be addressing those if
not right now with Apollo female within the week so I’m going to go ahead and
get jump right into it so Scott one of our listeners wants to know is does this
new liquid layer work in non vacuum environments yes it it relies upon
oxygen being present to initiate that polymerization reaction so it can work
anywhere where an oxygen leak may occur re um I suppose in addition to that it’s
what if it’s one side is oxygenated and one side is some other gaseous substance
as long as the we pressurize the site with a greater pressure contains oxygen
that was so that would push oxygen through any breach that would form that
would initiate the reaction if the other side was a was a higher pressure we
would have to test it to see if the amount of action present would actually
be enough to initiate the reaction okay great say this has been used this someone
instance Institutes this technology in their fair applications and make it’s
multiple uses it gets multiple functions over time is it possible at the liquid
layer in the middle could run help and you could have yes yeah it can and that
is one of the potential limitations of this technology this is designed to be a
one-time use only if you hit in the exact same area where it has already
been healed it will probably punch out that solid plugg and there may or may
not be enough liquid to fill into that gap and reseal it that’s also one of the
reasons why we decide to make this a multi-layered healing system so we have
those front and back layers made of us with other material like sterling or PPG
and we had hope that one of those plastics was able to seal itself up and
seal that second breach that would happen so this isn’t this is just
product question in my mind I’m shredder listener wants to know as well
he said it was a one-time meet so that one time used for that a specific spot
or that yes this is it thought it could be I use being like two inches away yes
it has the intention great okay the chances of micrometeoroid hitting
exactly the same splat twice is probably pretty low agreed agreed
but I was just wondering for non space environments certainly they might be
more concerned about puncture you to know if your areas close by it’s things
like that so on to the next question do be self-healing plastics only work at
speed I know you said you used ballistics and to simulate
micrometeoroids which are coming in quite quickly yo do they does it work
for slower punctures so the the plastic see this Erland in the PPG only work at
high velocity now the testing that was done of those was a firing bullets that
were at a kilometer a second going slower than that might not cause those
to heal the healing action of those plastic depends on the impacts like
heating up as the bullet passes through if it’s slower it’s not going to eat up
as much and it may it may not heal the liquid
layer on the other hand doesn’t rely so much on the velocity it’s just the
presence of oxygen that is needed to initiate that solidification reaction
that would form that solid clog again so the reason why we incorporated this
multi layer to multi layers in the system so that for whatever type of
damage would happen at least one of these mechanisms can kick in to see a
level other it’s the reactive liquid or one of the two plastic layers fantastic
I’ve got one for Kim here what comes with the license for this technology so
what comes with the own license is the information typically found in the
patent so it’s the information you will probably get a little bit of the
inventors time but not much they’ll be able to ask a few questions and some
instances of a materialism bulb you can get a sample of the material by using an
MTA and material transfer agreement of course they do get some right – yeah i
reproducibly yes exactly I’m sorry yes exactly don’t want to
don’t know Dorner for Google yes um but of course that is included in a license
anything right to use the patent that’s exactly right thank you for another one
for Scott here can this be useful a submerged environment so 600 water maybe
um something I actually came up at my at my dissertation defense would ask you
that the chemistry as it is right now probably won’t work with water but I
think with some tweaks to the chemistry does that the concept could be
implemented it would take some additional research in order to modify
the system’s up but I do think it’s feasible okay I got a compound question
here someone wants to know if the liquid is flammable toxic and if it’s a solvent
it is so it’s not in a fault it’s a liquid and the component of the
formulation are either or it’s most of the monomer was about one for one or two
percent of the initiators the tributyl boring
as far as its toxicity we generally we think the superior is generally safe to
use that we haven’t in-depth investigated as toxicity for
flammability the attractant of boring that material in its pure form is quite
difficult and dangerous to handle it is very reacted with oxygen and if you just
open up a container of this material it will react with oxygen get up and catch
yourself on fire but including it at a moderate concentration of one or two
percent we think that this material would be would be safe to incorporate
into a larger structure so we do we would certainly think that this would
have to be a desiccated further great city this is a long one in the event one
polymer layer heals but the other armorer side doesn’t run on the
anaerobic side because the liquid just seep out and there any way to mitigate
such an effect yeah that is a that’s a real that’s a real concern with this so
it’s something that glances off the outside of a habitat and say the outside
cracks but the inside doesn’t there’s no oxygen present now all liquids has some
kind of vapor pressure so that liquids going to seep out or just evaporate off
into into the vacuum that is difficult now again we because this is a
multi-layered system and you know in this case it’s good that the inner that
the inner layer didn’t break so at least the people inside are under no risk of
this happens but now you have a a problem where it might drain out the
liquid and render it useless throughout the rest you know throughout for impact
elsewhere besides that one way to mitigate this we think might be to using
a liquid with very low or essentially no vapor pressure such as modifying the
monomers to be ionic liquids another way is to design a much more sophisticated
middle layer so instead of just having large amounts of those liquid present
you could design some kind of vascular networks that would allow you to pump
the liquid throughout this layer so even if you did lose some liquid you
then still replenish it this might also require an astronaut to go outside and
put a patch over this crack but this at least having this mechanism available
will allow you to refill the system with the reactive liquid fantastic well first
I wasn’t sure you’d have an answer for that and I think probably they’re going
to be our last question here this probably one is the most obvious and if
this is if this liquid layer is supposed to react with oxygen how in the world
did the work in space I’ve gotten I’ve gotten that question a lot at various
presentations and even at my defense the this is this is intended to be used
where there is oxygen on one side of a barrier and no oxygen on the other so
you have a pressurized environment with atmosphere and on the outside you have a
queue or near vacuum conditions and if it was designed to be used where if this
wall gets punctured now obviously the atmosphere that is
inside under pressure will leak out through that hole and it’s that oxygen
the oxygen that is leaking out through that hole that will initiate the series
of reactions to turn that liquid into a solid so obviously there’s no oxygen in
space but we’re not using are not using what’s available in space we’re using
what’s available inside the pressurized environment fantastic well if we didn’t
get to your question during the live Q&A session today we like I said earlier we
will be following up by email what’s in the next week if you have any questions
do please submit them you can send it to that the email address you see on the
screen currently and of course that you can find us on our website and submit
questions through there and we’ll be glad to get to you is within the next
week if you submitted anything during the webinar and if you submit anything
after we’ll get back to you as soon as we can and once again I just want to
thank everyone for your time and joining us today and we look forward to having
you join us on our next webinar

Glenn Chapman

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