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


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



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Opti#i)ation of recursor +oncentrationOpti#i)ation of recursor +oncentration



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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.



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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.


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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