self healing materials-2
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SELF-HEALINGSELF-HEALING
MATERIALSMATERIALS
Cristina Resetco
Polymer and Materials Science
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Motivation: Self-healing materials are smart materials that can
intrinsically repair damage leading to longer lifetimes, reduction of
inefficiency caused by degradation and material failure.
Applications: shock absorbing materials, paints and anti-corrosion
coatings.
Outline
(! Restoration of Conducti"ity #ith $$%-$C&' Charge-$ransfer Salts
(! Self-)ealing Materials #ith *nterpenetrating Micro"ascular
&et#orks
(+! Coaial lectrospinning of Self-)ealing Coatings
(! &anoscale Shape-Memory /lloys for 0ltrahigh Mechanical 1amping
Self-Healing MaterialsSelf-Hea
ling Materials
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Self-Healing MaterialsSelf-Healin
g Materials
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Self-)ealing MaterialsSelf-)eali
ng Materials
a) damage is inficted on the material
b) a crack occurs
c) generation o a 2mobile phase3triggered either bythe occurrence o damage (in the ideal case) or byexternal stimuli.
d) damage is removed by directed mass transporttowards the damage site and local mendingreaction through (re)connection o crack planes byphysical interactions and/or chemical bonds
e) ater the healing o the damage the previouslymobile material is immobilised again, resulting in
restored mechanical propertieshttp:44###.autonomicmaterials.com4technology4
http://www.autonomicmaterials.com/technology/http://www.autonomicmaterials.com/technology/ -
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Material DesignMaterial Design
Self-)ealing MethodsSelf-)eali
ng Methods
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Restoration of Conductivity withRestoration of Conductivit
y with
TTF-TCNQTTF-TCNQCharge-Transfer SaltsChar
ge-Transfer Salts
A new microcapsulesystem restoresconductivity inmechanically
damaged electronicdevices in which therepairing agent is notconductive until its
release.
Moore, 5. et al. Adv. unct. !ater. "#$#, "#, $%"$6
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&onductive healing agent is generated upon mechanical damage.
'wo core solutions travel by capillary actionto the relevantdamage site beore orming the conductive salt.
'he maor advantage o this approach is greater mobility ofprecursor solutionscompared to suspensions o conductiveparticles.
estoration o &onductivity withestoration o &onductivity with''*'&+''*'&+&harge*&harge*
'ranser -alts'ranser -alts
Moore, 5. et al. Adv. unct. !ater. "#$#, "#, $%"$6
Tetrathiafulvalene Tetracyanoquinodimethane
tetrathiaulvalene6tetracyanouinodimethane
&on-conducting &on-conducting Conducting
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igure $. ptical microscope images rom A) an attemptto encapsulate crystalline ''*'&+ salt in 0A, 1) !&scontaining powdered ''*'&+ salt suspended in 0A2inset3 ruptured !&s containing powdered '''&+ saltin 0A, &) ''*0A !&s, and 4) '&+*0A !&s. All scale barsare "##mm.
$$% and $C&' #ere indi"idually
incorporated into microcapsule coresas saturated solutions in chloroben7ene
(PhCl!, ethyl phenylacetate (P/!, and
phenyl acetate (P/!.
ol!"urea-for#al$e%!$e& "'F&
core(s%ellmicrocapsules #ere
prepared using an in situ
e#ulsification pol!#eri)ationin an
oil-in-#ater suspension.
Microcapsule S!nt%esisMicrocapsule S!nt%esis
lectron impact mass spectra of the
dried microcapsule core solutions
confirmed the presence of $$% and
$C&' in the microcapsules.Moore, 5. et al. Adv. unct. !ater. "#$#, "#, $%"$6
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!icroencapsulation o 4&04 utili5ing acid*cataly5ed in situ polymeri5ation o urea with
ormaldehyde to orm capsule wall.
Microencapsulation *! in-situ ol!#eri)ationMicroencapsulation *! in-situ ol!#eri)ation
1rown, 6. et al.2 7. !icroencapsulation, "##8, vol. "#, no. 9, %$:6%8#
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;hen mixtures o '' and '&+microcapsules were ruptured, a dark*brown
color was immediately observed, indicative othe ''*'&+ charge*transer salt ormation.
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igure %. measurements o analytes on glass slidesmeasured between two tungsten probe tips spaced
approximately $##mm apart or neat ruptured ''*0A,'&+*0A, and ''*0A3'&+0A in a $3$ ratio (wt?)microcapsules.
Restoration of Conducti"ity by $Restoration of Conducti"ity by $$%-$C&'$%-$C&'
Charge-$ransfer SaltCharge-$ransfer Salt
Moore, 5. et al. Adv. unct. !ater. "#$#, "#, $%"$6
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Opti#i)ation of recursor +oncentrationOpti#i)ation of recursor +oncentration
Moore, 5. et al. Adv. unct. !ater. "#$#, "#, $%"$6
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Self-)ealing Materials #ith *nterpenetrating Micro"ascularSelf-)ealing Materials #ith *nterpenetrating Micro"ascular
&et#orks&et#orks
)ealing strategy mimics
human skin, in #hich a minor
cut triggers blood flo# from
the capillary net#ork in the
underlying dermal layer to
the #ound site.
8ey ad"ances in direct-#rite assembly:
$#o fugiti"e organic inks possess similar
"iscoelastic beha"ior, but different temperature-
dependent phase change responses.
)ansen, C. et al. Adv. !ater. "##:, "$, $6=.
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1irect-9rite /ssembly #ith 1ual %ugiti"e *nks1irect-9rite /ssembly #ith 1ual %ugiti"e *nks
(a! poy substrate is le"eled for #riting
(b! 9a ink (blue! is deposited to form one net#ork
(c! Pluronic ink (red! is deposited to separate net#orks
(d! 9a ink is deposited to form nd micro"ascular net#ork
(e! 9a ink "ertical features are printed connecting to both
net#orks
(f! oid space is filled #ith lo# "iscosity epoy
(g! /fter matri curing, pluronic ink is remo"ed
(h! oid space from pre"ious pluronic net#ork is re-infiltrated #ithepoy
(i! 9a ink from both micro"ascular net#orks is remo"ed
(;! &et#orks are filled #ith resin (blue! in one net#ork and
hardener (red! in the second net#ork
)ansen, C. et al. Adv. !ater. "##:, "$, $6=.
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+oa,ial Electrospinning of Self-Healing +oatings+oa,ial Electrospinning of Self-Healing +oatings
)ealing agent encapsulated in a bead-on-string structure
and electrospun onto a substrate.
A$vantagesA$vantages
Park, 5. et al. /d". Mater.
==, , >?6>>
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One-Step +oa,ial Electrospinning EncapsulationOne-Step +oa,ial Electrospinning Encapsulation
Spinneret contains t#o
coaial capillaries
$#o "iscous li@uids are fed
through inner and outer
capillaries simultaneously
Electro-%!$ro-$!na#ic
forces stretch the fluid
interface to form coaial
fibers due to electrostaticrepulsion of surface charges
Park, 5. et al. /d". Mater. ==, , >?6>>
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%igure. SM images of a! the core6shell bead-on-string morphology and b! healing agent released from the
capsules #hen ruptured by mechanical scribing. c! %luorescent optical microscopic image of se@uentially spun
Rhodamine A (red! doped part / polysiloane precursor capsules and Coumarin ? (green! doped part A capsules.
d! $M image of as-spun bean-on-fiber core4sheath structure.
+ore(S%ell ea$-on-String Structures+ore(S%ell ea$-on-String Structures
Park, 5. et al. /d". Mater.==, , >?6>>
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Self-healing bypolycondensation of
hydroyl-terminated
P1MS and P1S
crosslinker cataly7ed
by organotin.
Self-Healing after Microcapsule RuptureSelf-Healing after Microcapsule Rupture
Park, 5. et al. /d". Mater. ==, , >?6>>
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%igure. SM images of scribed region of the self-healing sample after healing a! B
crosssection and b! top "ie# of the scribed region on a steel substrate.
Self-Healing *! ol!#eri)ationSelf-Healing *! ol!#eri)ation
%igure . Control and self-healing coating samples that #ere stored under ambient
conditions for months after B days salt #ater immersion.
Park, 5. et al. /d". Mater.
==, , >?6>>.c
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Nanoscale S%ape-Me#or! Allo!s forNanoscale S%ape-Me#or! Allo!s for
'ltra%ig% Mec%anical Da#ping'ltra%ig% Mec%anical Da#ping
Nanoscale illars of shape-memory alloys ehibit
mechanical damping greater than any bulk material.
San 5uan, 5. et al. &ature &anotech., ol. , ==>.
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1issipation of mechanical energy by re"ersible
transformation bet#een /ustenite and Martensite
due to stress.
San 5uan, 5. et al. &ature &anotech., ol. , ==>.
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Si)e Effect of +u-Al-Ni NanopillarsSi)e Effect of +u-Al-Ni Nanopillars
(! Sta*ili)ation of #artensiteby
small pillars that relie"e elastic energy
at the surface by crossing the entirespecimen
(! Sta*ili)ation of austenitebyelimination of martensite nucleation
sites
Cu-/l-&i pillars #ere producedby focuse$ ion *ea# "FI&
micromachining of surface
sections of Cu-/l-&i crystals.
San 5uan, 5. et al. &ature &anotech., ol. , ==>.
igure. -6! image o &u6Al6+i pillar, meandiameter o :## nm.
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+o#parison of Hig% Da#ping Materials+o#parison of Hig% Da#ping Materials
Merit inde D 4 E94F9ma
9 6 dissipated energy per stress-release cycle
E9- maimum stored energy per unit "olume 6 GoungHs modulus San 5uan, 5. et al. &ature &anotech., ol. , ==>.
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