Smart Rubbers: Synthesis and Applications, 2nd Edition

112 Pages·2019·0.919 MB·English

by  Lorenzo Massimo Polgar, Machiel van Essen, Andrea Pucci, Francesco Picchioni

LorenzoMassimoPolgar,MachielvanEssen,AndreaPucci,FrancescoPicchioni
SmartRubbers
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Lorenzo Massimo Polgar, Machiel van Essen,
Andrea Pucci, Francesco Picchioni
Smart Rubbers
Synthesis and Applications
2nd Edition
Author
Dr.LorenzoMassimoPolgar Prof.AndreaPucci
NXPSemiconductorsNetherlandsB.V. UniversitàdiPisa
HighTechCampus60 DipartimentodiChimicaeChimicaIndustriale
5656AGEindhoven ViaGiuseppeMoruzzi13
Netherlands 56124Pisa
Italy
MachielvanEssen
TechnicalUniversityofEindhoven Prof.Dr.FrancescoPicchioni
Dept.ofChemicalEngineering&Chemistry UniversityofGroningen
POBox513 FacultyofScienceandEngineering
5600MBEindhoven ProductTechnology
Netherlands Nijenborgh4
9747AGGroningen
Netherlands
ISBN978-3-11-063892-9
e-ISBN(E-BOOK)978-3-11-063901-8
e-ISBN(EPUB)978-3-11-063931-5
LibraryofCongressControlNumber:2018966601
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TheDeutscheNationalbibliothekliststhispublicationintheDeutscheNationalbibliografie;
detailedbibliographicdataareavailableontheInternetathttp://dnb.dnb.de.
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Preface
‘Smartrubbers’aredefinedaselastomericmaterialsthatrespondtoexternalstimuli
through a macroscopic output in which the energy of the stimulus is transduced
appropriatelyasafunctionofexternalinterference.
The bulk of these materials generally consist of elastomers or materials with
rubberybehaviourandproperties,butdisplayasmartresponse.A‘rubber’istypi-
cally a polymer that completely recovers its original shape upon deformation as a
result of physical or chemical crosslinking of the macromolecular network. The
term ‘smart’ implies that the material displays a response to an external stimulus
andthatthisoccursinacontrolledmanner.
Researchintosmartrubbershasincreaseddrasticallyoverthelastfewdecades,
predominantlyduetothegrowingdemandof,andtheneedfor,improvedmaterials
fornewapplications.Incentivesforthesedemandsaregenerallybasedonsocietal
aspectssuchaseconomics(i.e.,costreduction)andsustainability.Thus,smartrub-
bers are not limited only to scientific aspects but also intersect with societal rele-
vance. An overview of how the research field of smart rubbers is divided and
connectedintoseveralcomponentsisshowninFigureP1.1.
Polymer class X
Stimulus Response class Applications Social relevance
Additives class Y
FigureP1.1:Schematicoverviewoftherelationshipbetweenthevariouskeyvariablesthatshould
beconsideredinthedesignofsmartrubbers.
The research field of smart rubbers covers multiple components. Providing an
updateofsmartrubbersforeachcomponentinonebookisnotpossible.Hence,the
authorshavetaken‘snapshots’ofseveralcontributionsconsideredsuitabletopro-
videparadigmaticinformationaboutthemaintopic.
First, an update is provided on the sustainable design of smart rubbers (Chap-
ter1),whichisahottopicthathasanevidenthighsocietalrelevance.Subsequently,
sensingrubbers(Chapter2)representatypicalapplicationofsmartrubbers,andare
discussed in the context of academic and industrial developments. Optically active
https://doi.org/10.1515/9783110639018-201
VI Preface
elastomers(Chapter3)areaddressedasanotherillustrativeexampleofadifferentre-
sponse category. Lastly, the combination of components required to formulate a
smart rubber in a specific response class of actuating elastomers are discussed in
moredetail.Thisdiscussionissubdividedintoshapememory(Chapter4),magneto-
rheological elastomers (Chapter 5), and dielectric elastomers (Chapter 6). Different
stimuliandapplicationsareentwinedthroughoutallchapters.
In this way, the authors provide an update of smart rubbers that is relevant,
interestingandunderstandableforindustry,scientists,experts,andstudents.
Contents
Preface V
1 Sustainabilityinthedesignofrubbermaterials 1
1.1 Bio-Basedrubbers 4
1.2 Recyclableandself-healingrubbers 6
1.2.1 Recyclingrubber 6
1.2.2 Reversiblecrosslinking 6
1.2.3 Self-healingelastomers 8
1.2.4 Autonomousself-healingbydamage-triggeredsmart
containers 10
1.2.5 Intrinsicself-healingviareversiblecrosslinking 11
1.2.5.1 Self-healingthroughnon-covalentinteractions 12
1.2.5.2 Thermo-reversiblechemicalinteractions 15
1.3 Concludingremarks 16
References 16
2 Environment-sensingrubbers 23
2.1 Introduction 23
2.2 Mechanicalsensors 24
2.3 Temperaturesensors 28
2.4 Chemicalsensors 31
2.5 Conclusions 33
References 33
3 Opticallyactiveelastomers 37
3.1 Introductionandbasicprinciples 37
3.2 Chromogenicelastomers 38
3.3 Tropogenicelastomers 46
3.4 Elastomericlenses 48
References 50
4 Shape-memoryelastomers 51
4.1 Introduction 51
4.2 Heat-inducedshapememoryinshape-memoryelastomers 52
4.3 Otherexternalstimuli 59
References 64
5 Magnetorheologicalelastomers 67
5.1 Backgroundandbasicprinciples 67
5.2 Mechanicalproperties 68
VIII Contents
5.3 Behaviourinamagneticfield 71
5.4 Electricalpropertiesinmagneticfields 75
5.5 Applications 77
References 79
6 Dielectricelastomers 81
6.1 Introductionandbasicprinciples 81
6.2 Tailoredelastomers 83
6.3 Additivesindielectricelastomers 86
References 88
7 Futureoutlook 89
Abbreviations 91
Index 93
1 Sustainability in the design of rubber materials
Sustainabilitybecomesanevermoreimportantandunavoidabletopicwhendesigning
materialsorchemicalproducts.Thisisalsothereasonforthevastincreaseinresearch
output on this topic and the number of scientific articles having ‘sustainability’ as a
majorkeyword(Figure1.1).Sustainablematerialscanbedefinedbroadlyasmaterials
thatcanbeproducedandreusedindefinitelywithoutaffectingthehuman–ecosystem
equilibrium. Three major issues should be taken into consideration for the develop-
mentofasustainablematerial:theproductionprocess,carbonfootprintandpurpose
ofthematerialattheendofitsproductlife.
First, the process to develop and produce the material should be sustainable.
Hence, an energy-neutral process is required and all solvents and utility streams
mustultimatelyberecycledwithouttheproductionofanywaste.Agoodexampleis
therecentlydevelopedprocesstoextruderubbersusingsupercriticalcarbondioxide
(scCO)[1].Besidesbeingagoodandgreensolvent,scCO improvesthedispersionof
2 2
materials such as fillers or other polymers in the rubber matrix [1, 2]. After the pro-
cess, the harmless solvent is easily fed back into the environment by releasing the
pressure. The focus of this book is materials (smart rubbers) so, rather than smart
processing, the carbon footprint of a material and its recyclability will be discussed
in more detail because they are more related to the material itself. As both compo-
nentsareimportant,theycannotalwaysbedistinguished(Figure1.2).
Currently, most rubber products consist of elastomers that originate from the
lower-leftquadrant.Theseelastomersareusuallyoil-basedandnon-recyclabledue
to the presence of irreversible crosslinks. A significant amount of the rubber prod-
uctsthatweuse(≈40%ofallrubberused[3,4])stillcontainalotofnaturalrubber
(NR),whichisanaturalpolymericcompoundproducedfromthelatexofHeveabra-
siliensis (which mainly contains cis-polyisoprene). This amount is ever decreasing
asNRisbeingreplacedbysyntheticrubbersthathavebeendevelopedtomeetthe
highlydemandingrequirementsforspecificapplications.Agoodexampleofsucha
specific application that requires very specific material is sealants. The neoprene
groupofsyntheticrubbersthatisgenerallyusedforsuchapplicationsisverystable
with respect to NR and is, therefore, used for multiple applications such as wet-
suits,laptopsleevesanddurablemedicaldevices.Thelowelectricalconductivityof
theseneoprenerubbersalsomakesthemusefulasaninsulatorinelectricalwiring.
NR is a poor candidate for such applications because the high number of unsatu-
rated carbon–carbon double bonds makes the elastomers too reactive with other
chemicalstobewidelyusedforsuchapplications.Recentdevelopmentsusingbio-
mass as a feedstock for base chemicals have led to the replacement of some syn-
theticrubbersbybio-basedalternatives.Twoexamplesofsuchbio-basedsynthetic
rubbers are discussed in Section 1.1. Even when using NR or bio-based elastomers
in a rubber product, the final products are not completely bio-based due to large
https://doi.org/10.1515/9783110639018-001
2 1 Sustainabilityinthedesignofrubbermaterials
10000
9000
8000
s
n
oy
catibilit 7000
blina
ber of scientific puh a focus on sustai 6543000000000000
umwit
N 2000
1000
0
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6
0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2
Figure1.1:Theexponentialincreaseinscientificarticlethatfocusonsustainabilityoverthelast
decadesasgeneratedfromthe‘webofknowledge’.
Specialty thermosets
Drop-in replacements
B
Natural rubber io
-b
a
s
e
d
Non recyclable Recyclable
Crosslinked rubbers Fo Thermoplastics
ss TPE, TPV
il-fu
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Figure1.2:Theenvironmentalaxis.Thebio-basedcharacterandrecyclabilityofmaterialsasindi-
vidualcomponentsofsustainability.ReproducedwithpermissionfromDr.MartijnBeljaars.