Kind: captions
Language: en
here are two metal cylinders and a
single drop of superglue once it sets
you can literally hang from that one
drop of
adhesive oh my God that is
crazy so how is super glue so strong
that's what I want to find out and along
the way we're going to learn how it sets
so quickly why it's so good at sticking
to skin how it saves lives and how it
might even help solve our plastic
pollution problem plus if it's so strong
one single drop can easily lift over 3
tons why is it weak in certain
circumstances mom's going to kill us in
1942 the US was at War and to accelerate
the production of gunsights the Eastman
Kodak company was looking for a clear
plastic that could be cast instead of
grinding glass lenses chemist Harry
couver was working on a compound called
cyano acon
it looked promising but it had the
unfortunate tendency to stick to
everything it touched couver called it a
severe pain and as the war wound down
Kodak gave up on finding a plastic
replacement and kept on making gunsights
out of
glass by 1951 couver was again trying to
develop a clear plastic this time for
Jet Plane canopies if he could just
solve the stickiness problem
cyanoacrylate could work
couver showed the material to his
cooworker Fred Joiner but gave him
strict instructions I told him look
don't take a refractive index of this
material if you do you're going to wreck
the refractometer cuz it's going to
stick it together but after testing 99
other compounds Joiner had forgotten so
he prepped the 910th test by smearing
cyanoacrylate between two prisms after
taking the measurement Joiner discovered
he couldn't pull the prisms apart
he panicked the refractometer worth
nearly $10,000 adjusted for inflation
was
ruined but instead of getting angry
couver had a flash of insight he got a
sample of cyano acrylate and began
gluing together anything within reach
glass plates rubber stoppers metal
spatulas wood paper in all different
combinations he said everything stuck to
everything almost instantly and with
bonds I could could not break apart with
this discovery he dubbed the compound
Eastman 910 adhesive as it was the 910th
substance tested in the company's search
but nowadays everyone calls this super
glue so how does it work so quickly with
such strength on so many different
things bonds almost anything a plastic
knob a plastic plug a rubber boot a
metal Broach a fishing rod a cycle grip
model planes and model trains a door
knob screw a flashlight case the broken
trim on superglue in the tube is a
liquid of identical monomer molecules
the molecule is ethyl
cyanoacrylate when you put it between
two surfaces the liquid flows into all
the pores and crevices then the monomers
start reacting with each other joining
to form long polymer chains this turns
the glue from a liquid into a solid and
at this point it can no longer be pulled
out of the cracks and crevices so it's
stuck in place and the two surfaces are
connected if you're ever trying to glue
surfaces that are too smooth this is
probably the reason superglue sticks
poorly there are few crevices or pores
for it to cling to to fix this you can
sand the surfaces to introduce some
surface texture that way when the liquid
glue solidifies it's stuck in the
cracks but what triggers the monomers to
solidify instead of staying liquid like
they are in the
tube well ethyl cyanoacrylate is primed
to react because it has two double bonds
and one triple bond close
together what makes it so reactive is
you have a double bond attached to a
nitri group and an ester group and the
unique part about that is the chemistry
of those groups make that double bond so
electron deficient the oxygen and the
nitrogen atoms attract electrons more
than the carbons so that leaves this
carbon slightly positively
charged it is hungry it is looking and
anything even slightly electr negative
it will attack and it'll start a
reaction in the presence of a negative
ion the carbon double bond breaks and
four single bonds form but the nitr and
EST groups are so electronegative they
pull the extra electron across the
molecule making this carbon negative
that invites another slightly positive
Carbon on a separate monomer to attack
and now they're chemically linked
together the start of a polymer chain
and once that goes now it has the
ability to go react with all those other
superglue hungry monomers and and
rapidly pize it's it's a really really
chemically reactive species that single
initiator started a chain reaction the
next monomer again pulls across the
electron and more and more monomers bond
together forming longer and longer
chains until the superglue has
solidified it normally takes between 10
and 30 seconds to set this was much
faster than other adhesives avail able
in the 1950s a lot of glues like white
glue and glue sticks work by drying out
so you have to wait for the water to
[Music]
evaporate but with Superglue it's almost
the opposite while I was prototyping
snatoms I 3D printed these plastic
shells and superglued them together one
day I was trying to open a bottle of
superglue where the cap had gotten glued
onto the nozzle so I tried twisting it
off with my teeth but the bottle
exploded filling my mouth M with
superglue and I was thinking well I
might have a few seconds to spit it out
with the saliva in my mouth before it
set but the superglue actually hardened
immediately it stuck to my teeth and my
tongue I had to get my now wife to pick
it out of my teeth with tweezers luckily
it didn't glue together anything
essential I think it's because it
solidified so rapidly and the reason it
did that is because the polymerization
of superglue is actually triggered by
water specifically it's the slightly
negative oxygen atoms in the polar water
molecule and the negative hydroxide ions
in water that often break open the
carbon double bond initiating the
formation of chains and water is
everywhere I mean there's moisture in
the air little bits of water on most
surfaces or absorbed into materials like
Fabrics that's why superglue sets
rapidly on almost every surface each
water molecule can initiate the
formation of a polymer chain there's a
forensic technique that uses superglue
fumes to pull fingerprints from
nonporous surfaces when you grab
something your hand leaves behind
moisture and oils that are perfect for
superglue to bind with and this also
makes skin ideal to stick to there are a
lot of wrinkles and pores for superglue
to seep into plus the protein collagen
has a number of negative regions that
can initiate the polymerization reaction
and bond directly with am monomer so
your skin is the perfect sort of surface
for superglue to stick to and that's why
it's so hard to get off some of your
molecules literally become part of the
polymer chain there's a medical case
study where someone got cyanoacrylate
all over his hands so he quickly went to
wash it off with soap and water but that
accelerated the polymerization reaction
and his hands were stuck together so he
went to multiple medical professionals
and he got terrible advice they tried
alcohol water and soap they also
attempted physical separation and he
went to consult cosmetic surgery but
finally someone suggested acetone
acetone or nail polish remover dissolved
the glue and released his hands now
unfortunately the bottles for some types
of superg glue look incredibly similar
to those for eye drops so there are
hundreds of cases of people putting
superglue directly into their eyes in
that case acetone is not the solution
don't try to separate your eyelids just
seek medical
attention superglue is strong to
demonstrate this and promote his new
product cover went on a game show he
showed that with only a single drop of
glue he could lift himself and the host
into the air here we go on one drop of
glue after 24 hours it would support
something like 15,000 LB One Drop of
glue now doctor you must be very proud
of this I imagine many years of research
went into its Discovery huh no as a
matter of fact there wasn't Gary this
discovery was purely by accident bully
bre superglue polymers are almost all
single chains running linearly between
the surfaces they have a directionality
to them kind of like wood grain the
chains are densely packed with some
cross linking between them and this
makes the polymer fairly rigid and it's
about as hard as a hard hat this makes
it strong in compression
under tension superglue is strongest
when you pull in the same direction as
the chains the tensile strength of
superglue can be upwards of 25
megapascals which is similar to other
polymers meaning a square patch just 5
cm on a side could suspend a fully grown
African
elephant but superglue also has its
weaknesses it is brittle so if there's a
Sudden Impact it just kind of falls
apart as the superglue is very quickly
reacting it usually produces really
short polymer chains that have a matrix
with built-in stress anytime you have
stress in a material it it's a potential
failure point the thing that makes it a
really good adhesive is kind of its
Achilles heel in some cases polyethylene
polypropylene nylons like those squishy
Plastics they their polymer chains and
their chemistry are such that they can
absorb a lot of impact if a Force comes
they they'll kind of
deform whereas in the the chains of a
superglue polymer it doesn't have the
ability to do that so any impact will
come and it'll physically break those
rigid bonds and it'll also kind of be
absorbed in those stress points and
it'll cause it the whole thing to
fracture superglue is also weak if a
force is applied perpendicular to the
polymer chains that is it's weak in
sheer during this Shear test the stress
releases breaking the superglue
Bond so Shear is kind of a combination
of forces so you kind of have like a
compression and like a friction going on
tension is a pretty unidirectional force
and like the polymer chains are able to
deform enough however in sheer you have
a more Dynamic set of forces going on
and and they're just kind of breaking
all all at once sheer force doesn't get
spread even ly it's highest at the edges
and lower in the middle and since
superglue is so brittle it can't
redistribute this stress causing the
bond to fail it's even worse if you grab
one end of a surface and try to peel it
back in that case all that force is on a
few polymers so the chains break one by
one like a zipper
unzipping two long bars super glued
together could be strong since there's a
lot of surface area but if one end
breaks the rest can easily peel off off
now a bond breaking is bad but there are
some materials that super glue won't
even stick to at all so here we
have a milk bottle and this is made out
of a plastic called polyethylene we're
going to put one drop right
here but it's so weak you can see that
the glue has made a
perfect little
film and it doesn't stick whatsoever the
materials that superglue does not bond
to they they fall into a category of
materials that are known as chemically
inert and by inert it just means that
they don't have reactive sites so
superglue is so reactive because it is
so electron deficient it's looking for
any source of electrons but you have a
polypropylene or a polyethylene or a
Teflon and carbon loves carbon and
carbon is not sharing its electrons so
there is nothing on the surface surf
that is willing to donate any reactivity
even if you add initiators Say by
spraying water it still doesn't work
that's because these materials are
hydrophobic and nonporous if you spray
like a a polypropylene sheet um with
water it'll just fall off right you know
if you can think of like the beating up
of water on a hydrophobic surface so if
you pour Super Glue on top of water
it'll just like you'll just get like a
clump of super glue on it and then you
can just peel it off
most superglue specifically warns
against using it on polyethylene and
polypropylene because it won't stick but
this is actually a good thing you have
to have something that superglue won't
stick to so it can be contained and
stored without
setting superglue quickly found
industrial applications its first sale
was to Mason and hangar in 1956 who used
it to assemble atomic bombs soon
different additives were devised to
change the properties of pure ethyl
cyanoacrylate the monomers by themselves
are very runny almost like water so
companies added thickening agents like
fumed silica to turn it into a gel fumed
silica forms Branch structures that
increase viscosity some acid is often
added to inhibit polymerization in the
tube if you want to speed up the setting
of superglue one way is to add more
negative ions the initiators that start
the polymerization reaction you can buy
accelerators specifically for this
purpose off the shelf but a number of
diyers and handymen use baking soda
sodium byc carbonate it reacts with
moisture in the air to produce hydroxide
ions so when you add superglue it sets
even faster due to all those ion
initiators plus it forms a really hard
composite substance you can layer
superglue and baking soda to strengthen
a joint and fill gaps it can even be
drilled or sanded after setting
it's interesting to see how baking soda
in solution speeds up the polymerization
of superglue if you take pure water and
pour in superglue you get a bunch of
little plastic droplets the glue sets
quickly but not fast enough to keep the
whole stream connected but with baking
soda dissolved in the water the
superglue sets even
faster this creates a continuous length
of polymer which is really cool to see
but the resulting plastic is fragile and
can easily be
crushed if you want to glue things
underwater with superglue the key is
actually to slow the polymerization down
with a gel cyanoacrylate the thickeners
slow the reaction giving you enough time
to apply and detach objects wow there it
is glued
underwater it's not even a perfect fit I
didn't put it together quite right but
it's still
stuck one day C's eldest son was making
a model when he accidentally cut his
finger as a quick-thinking and
experimentally minded father cver got
some superglue he brought home from the
lab and applied it to the cut it
instantly sealed shut cover immediately
saw its potential in medicine and he
went to work he envisioned a glue that
could completely replace sutures but his
team soon ran into three key problems
first as superglue sets all those bonds
formed forming release Heat this is a
standard cotton ball just going to add
some liquid
superglue 86 oh my gosh it's starting to
smoke 93
108 wo make my eyes water 120 if you do
this at home wear goggles and probably a
respirator and probably do it outside
I'm feeling it now it is hot hot to the
touch the cotton has a lot of surface
area and it's absorbed a lot of water so
the superglue sets even faster than
usual and releases all its heat at once
if I get it on my skin the temperature
increase wouldn't be as dramatic but
it's enough to irritate a
wound the second problem is that over
time superglue in the body breaks down
and some of the things it breaks down
into are toxic chemicals like f Malahide
and finally superglue is hard and
brittle unlike us we are mostly just
squishy bags of meat and water so an
adhesive for living tissue needs to be
soft and flexible for the entire
duration of the healing
process remarkably couver and his team
found that all of these problems could
be solved with a single change to the
molecule simply increase the number of
carbons in the alkal
chain with longer carbon chains it takes
more time for the monomers to bind
together which slows SLS down the rate
of reaction this slows the rate of heat
released so there's not a significant
temperature increase all at once the
longer polymers also break down much
more slowly so the wound has enough time
to heal before the glue starts releasing
toxins into the body it's removed before
that
happens and finally since the reaction
is slower there's more time for the
monomers to float around and form longer
polymers these longer polymers can
absorb stress better than shorter chains
meaning the glue can Flex more without
breaking with the main problems
addressed couver submitted an
application to the FDA in 1964 for
medical
superglue the US military was very
interested in cover's adhesive and they
developed a medical superglue spray for
use in the Vietnam
War the spray saved lives in one case a
bullet hit a 24-year-old Soldier passing
through his kidney and liver after part
of his liver was removed they gave him
12 lers of blood that's enough to
replace all the blood in his body twice
over but the bleeding just wouldn't stop
by conventional methods he was gone but
then the surgeons sprayed superglue
directly on the liver the bleeding
stopped Vital Signs returned to normal
and the soldier
recovered despite its success on the
battlefield medical superglue was held
up in bureaucratic red tape for years so
long that couver had to abandon the in
the project it wasn't until 1998 that he
saw his dream of a medical glue approved
a two octal cyanoacrylate called
dermabond medical superglue has now
grown to be a $900 million a year
industry in the 74 years since coover's
accidental Discovery cyano acrylate has
grown to become a$3 billion industry but
its impact doesn't stop there because
now scientists are turning to couver
original research exploring its use as a
plastic and it could well solve one of
the biggest problems the planet faces
how to recycle the mountain of plastic
we produce each year manufacturers can
shred melt and reform other Plastics but
the polymers degrade so the quality is
worse and the process generates
microplastics so you can only recycle
mechanically and thermally like that a
certain number of times before you get a
material that's kind of useless it's
still will sit in the environment and it
won't break down but it's not useful but
superglue is unique if you heat it up to
210° cus it'll break back down into pure
monomers these can be distilled and then
reactivated back into fresh polymer we
have a starting material we make it into
a plastic and then under a certain
stimulus we can turn it back to that
starting material so let's see if we can
make a plastic from this you know cuz
the goal of a deep polymerizable plas
plastic is that it's sustainable right
there are just two problems first how do
you cast something that sticks to
basically everything and second
superglue on its own is brittle so how
do you stop it from breaking the big
problem is the handleability that that
was kind of the original problem they
found that okay this isn't a great
plastic because it sticks to everything
that's how they discovered that it was
an excellent adhesive so we were faced
with that same problem but couver didn't
have the modern Plastics we have today
polypropylene polyethylene and Teflon
are so inert they don't activate
superglue so they are the perfect
materials to handle the
monomers so we were able to actually
handle it so that that was you know huge
check we can actually work with this
material next to reduce brittleness you
need Superglue to form long chains that
tangle together and this problem can
actually be broken down into two parts
first a lot of initiators means lots of
short polymer chains second as the
superglue sets the existing chains
freeze and they can't connect together
there also might be some unused monomers
that can't get into the right spot to
attach if you can solve both these
issues you get longer chains the first
fix is to use a very weak base by mixing
in a little bit of this weak base there
are enough initiators to start the
polymerization reaction but not too many
so the polymer chain end up being longer
we use DMSO dimethyl Sul oxide which in
no other context would be used as an
initiator um but it was just
electronegative enough that we were able
to initiate a reaction that could go
slowly and proceed in a way that
produced a nice solid
plastic next you need a solvent in this
case acetone and and what a solvent is
is it's just a media that dilutes the
conditions it does not participate in
the reaction usually it provides
additional Mobility after mixing the
glue and initiator into the acetone the
mobile polymers are able to form even
longer more stable chains than
usual and after a while all the
superglue sets the acetone evaporates
and the new plastic is
[Music]
removed to reuse it just heat it up and
distill it to get back super glue
monomers so I would on average get
around 93% which is excellent compared
to that even the most widely recycled
Plastics can't return to the same
quality and they can only be downcycled
once or twice before ending up in
landfill I'm superg glue's biggest fan
obviously but I I hope that it can
actually have a real impact in terms of
sustainability and kind of
revolutionizing how we look at Plastics
and how we look at materials that you
know we've existed with for for decades
you know okay what if we use this for
something else cver said it took the
right mindset to see cyanoacrylate as a
great adhesive the first time he worked
with it he was thinking about gunsights
and nothing but gunsights its sticky
qualities were a pain the second time he
encountered it his colleagues fixated on
the broken refractometer but he could
finally see the quality that frustrated
him as a benefit and then after Decades
of researchers only viewing it as a
useful adhesive it took another flash of
inspiration to see its potential as a
plastic once more as cver said this
should serve as a reminder to all of us
to be open-minded and curious enough to
pursue unexplained events and unexpected
results which may unlock new secrets and
lead to new and exciting discoveries of
the
[Music]
future C's ability to look Beyond
roadblocks and see the breakthroughs on
the other side is a skill that every
great innovator shares it's not some
kind of rare genius it just takes strong
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