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Strategies for Molecular Engineering of Macroscopic Adhesion and Integrity Focusing on Cellulose Based Materials
KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Fibre- and Polymer Technology, Fibre Technology. (Fibre Technology)ORCID iD: 0000-0001-6180-8917
2019 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Many aspects of modern human life pose a strain on the delicate ecosystems around us. One example is marine litter – mainly various plastic items – which accumulate in the marine environment, where they cause problems for the fauna, such as ingestion and entanglement.The widely used plastics offer many advantages for packaging, such as low cost and easy processing into many shapes. However, in addition to their low biodegradability leading to their persistence and accumulation in nature, they are largely manufactured from petroleum,a non‐renewable resource. Clearly, it would be highly desirable to exchange the petroleum‐based materials for biodegradable ones from renewable resources. Cellulose, as the most abundant biopolymer, is one choice. There are however challenges in terms of replacing currently used plastics with cellulosic materials. One is the low ductility and formability of cellulose. Various efforts are undertaken to increase the formability of cellulose. One approach to increase the renewable fraction within a material is to utilise the intrinsic stiffness and strength of cellulose to increase the structural integrity of a composite. To fully optimise these types of materials, a fundamental understanding of the interaction across interfaces within the material is essential. The main objective in this thesis was to elucidate strategies to measure, to tune and to control the interaction across interfaces. Specific polymers were designed and synthesised which could be used to modify surfaces to achieve a wet adhesion as high as that of mussel foot protein. Many properties of the joint were tuneable by varying length and structure of the polymer and amount of polymer deposited on the surfaces. A method to accurately evaluate interfacial adhesion between a chemically modified cellulose material and another surface was successfully developed, using nanometre smooth cellulose probes exhibiting bulk material properties. Two composite materials containing cellulose as reinforcing element were successfully prepared,utilising different strategies to control and enhance the interaction between the composite constituents. Together, these findings contribute to the knowledge of how to evaluate and control the interaction across an interface.

Abstract [sv]

Vår moderna livsstil utsätter ekosystemen runtomkring oss för stora påfrestningar. Ett exempel bland många är all den plast som ackumuleras i världshaven och ställer till stora problem för vattenlevande organismer. Plaster har många olika användningsområden, bland annat som förpackningsmaterial, då det är relativt enkelt att framställa produkter i många olika former till ett lågt pris. Däremot är de flesta plaster som idag används storskaligt inte nedbrytbara i naturen, och tillverkas från råvara som inte är förnyelsebar. Av dessa skäl vore det önskvärt att byta ut de traditionella plastmaterialen mot andra material som är biologiskt nedbrytbara och från förnyelsebara källor. Cellulosa, det material som tillverkas av levande organismer i störst skala, är en klar kandidat. Detfinns dock utmaningar med att byta ut plaster mot cellulosa, såsom cellulosans låga töjbarhet och formbarhet. Det pågår forskning som syftar till att öka töjbarheten och formbarheten på olika sätt. En sätt att öka mängden förnyelsebar råvara i ett producerat material är att utnyttja cellulosans styvhet och styrka för att förbättra den mekaniska hållfastheten hos en komposit. För att till fullo utnyttja cellulosans potential krävs en grundläggande förståelse för interaktionen över gränsskikt mellan olika komponenter inom ett material. Den här avhandlingens huvudsakliga syfte vara att ta fram strategier för att mäta och styra interaktionen över ett gränsskikt. Polymerer, dvs. långa kedjelika molekyler, designades och framställdes. Dessa polymerer kunde användas för att modifiera ytor och uppnå en vidhäftningsförmåga i vått tillstånd som var lika stark som hos musselfotprotein. Många egenskaper hos fogen kunde finjusteras genom att variera längd och struktur hos polymeren och mängdpolymer som applicerades på ytorna. En metod för att tillförlitligt utvärdera interaktionen mellan en kemiskt modifierad cellulosayta och en annan yta utarbetades, genom att använda mycket släta cellulosasfärer (ytråhet på nanometerskala) och samtidigt bulkegenskaper hosmaterialet. Två kompositmaterial med cellulosa som förstärkande komponenet framställdes, där olika strategier utnyttjades för att kontrollera och förbättra interaktionen mellan komponenterna i kompositmaterialet. Sammantaget bidrar detta till kunskapen om hur interaktionen över ett gränsskikt kan styras och mätas.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2019. , p. 51
Series
TRITA-CBH-FOU ; 2019:63
Keywords [en]
blockcopolymer, cellulose, adhesion, ATRP, micelle
National Category
Materials Chemistry
Research subject
Fibre and Polymer Science
Identifiers
URN: urn:nbn:se:kth:diva-263075ISBN: 978-91-7873-353-8 (print)OAI: oai:DiVA.org:kth-263075DiVA, id: diva2:1366374
Public defence
2019-11-22, Q2, Malvinas väg 10, Stockholm, 10:00 (English)
Opponent
Supervisors
Funder
Swedish Research CouncilAvailable from: 2019-10-29 Created: 2019-10-29 Last updated: 2019-10-29Bibliographically approved
List of papers
1. Strong and tuneable wet adhesion with rationally designed layer-by-layer assembled triblock copolymer films
Open this publication in new window or tab >>Strong and tuneable wet adhesion with rationally designed layer-by-layer assembled triblock copolymer films
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2016 (English)In: Nanoscale, ISSN 2040-3364, E-ISSN 2040-3372, Vol. 8, no 42, p. 18204-18211Article in journal (Refereed) Published
Abstract [en]

this study the wet adhesion between Layer-by-Layer (LbL) assembled films of triblock copolymer micelles was investigated. Through the LbL assembly of triblock copolymer micelles with hydrophobic, low glass transition temperature (T-g) middle blocks and ionic outer blocks, a network of energy dissipating polymer chains with electrostatic interactions serving as crosslinks can be built. Four triblock copolymers were synthesized through Atom Transfer Radical Polymerisation (ATRP). One pair had a poly(2-ethyl-hexyl methacrylate) middle block with cationic or anionic outer blocks. The other pair contained the same ionic outer blocks but poly(n-butyl methacrylate) as the middle block. The wet adhesion was evaluated with colloidal probe AFM. To our knowledge, wet adhesion of the magnitude measured in this study has not previously been measured on any polymer system with this technique. We are convinced that this type of block copolymer system grants the ability to control the geometry and adhesive strength in a number of nano-and macroscale applications.

Place, publisher, year, edition, pages
Royal Society of Chemistry, 2016
National Category
Chemical Sciences Nano Technology
Identifiers
urn:nbn:se:kth:diva-199546 (URN)10.1039/c6nr05659h (DOI)000387427400024 ()27752695 (PubMedID)2-s2.0-84994128648 (Scopus ID)
Note

QC 20170116

Available from: 2017-01-16 Created: 2017-01-09 Last updated: 2019-10-29Bibliographically approved
2. Enhanced toolbox to tailor theproperties of Layer‐by‐Layer assembled triblock copolymer films
Open this publication in new window or tab >>Enhanced toolbox to tailor theproperties of Layer‐by‐Layer assembled triblock copolymer films
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(English)Manuscript (preprint) (Other academic)
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-263103 (URN)
Note

QC 20191104

Available from: 2019-10-29 Created: 2019-10-29 Last updated: 2019-11-04Bibliographically approved
3. Macroscopic cellulose probes for the measurement of polymer grafted surfaces
Open this publication in new window or tab >>Macroscopic cellulose probes for the measurement of polymer grafted surfaces
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2019 (English)In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 26, no 3, p. 1467-1477Article in journal (Refereed) Published
Abstract [en]

A synthesis protocol was identified to produce covalent grafting of poly(dimethyl siloxane) from cellulose, based on prior studies of analogous ring opening polymerizations. Following this polymer modification of cellulose, the contact adhesion was anticipated to be modified and varied as a function of the polymer molecular mass. The synthetic details were optimized for a filter paper surface before grafting the polymer from bulk cellulose spheres. The adhesion of the unmodified and grafted, bulk cellulose spheres were evaluated using the Johnson-Kendall-Roberts (JKR) theory with a custom build contact adhesion testing setup. We report the first example of grafting poly(dimethyl siloxane) directly from bulk cellulose using ring opening polymerization. For short grafting lengths, both the JKR work of adhesion and the adhesion energy at the critical energy release rate (G(c)) were comparable to unmodified cellulose beads. When polymer grafting lengths were extended sufficiently where chain entanglements occur, both the JKR work of adhesion and G(c) were increased by as much as 190%. Given the multitude of options available to graft polymers from cellulose, this study shows the potential to use this type of cellulose spheres to study the interaction between different polymer surfaces in a controlled manner. [GRAPHICS] .

Place, publisher, year, edition, pages
SPRINGER, 2019
Keywords
Grafted polymer, Cellulose, Contact mechanics, Adhesion, Johnson-Kendall-Roberts theory
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-247840 (URN)10.1007/s10570-018-2196-2 (DOI)000460617900004 ()
Note

QC 20190326

Available from: 2019-03-26 Created: 2019-03-26 Last updated: 2019-10-29Bibliographically approved
4. Molecular Engineering of the Cellulose-Poly(Caprolactone) Bio-Nanocomposite Interface by Reactive Amphiphilic Copolymer Nanoparticles
Open this publication in new window or tab >>Molecular Engineering of the Cellulose-Poly(Caprolactone) Bio-Nanocomposite Interface by Reactive Amphiphilic Copolymer Nanoparticles
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2019 (English)In: ACS NANO, Vol. 13, no 6, p. 6409-6420Article in journal (Refereed) Published
Abstract [en]

A molecularly engineered water-borne reactive compatibilizer is designed for tuning of the interface in melt-processed thermoplastic poly(caprolactone) (PCL)-cellulose nanocomposites. The mechanical properties of the nanocomposites are studied by tensile testing and dynamic mechanical analysis. The reactive compatibilizer is a statistical copolymer of 2-(dimethylamino)ethyl methacrylate and 2-hydroxy methacrylate, which is subsequently esterified and quaternized. Quaternized ammonium groups in the reactive compatibilizer electrostatically match the negative surface charge of cellulose nanofibrils (CNFs). This results in core-shell CNFs with a thin uniform coating of the compatibilizer. This promotes the dispersion of CNFs in the PCL matrix, as concluded from high-resolution scanning electron microscopy and atomic force microscopy. Moreover, the compatibilizer "shell" has methacrylate functionalities, which allow for radical reactions during processing and links covalently with PCL. Compared to the bio-nanocomposite reference, the reactive compatibilizer (<4 wt %) increased Young's modulus by about 80% and work to fracture 10 times. Doubling the amount of peroxide caused further improved mechanical properties, in support of effects from higher cross-link density at the interface. Further studies of interfacial design in specific nanocellulose-based composite materials are warranted since the detrimental effects from CNFs agglomeration may have been underestimated.

Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2019
Keywords
biocomposite, nanocellulose, reactive processing, mechanical properties, interphase, interface, biodegradable
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-255446 (URN)10.1021/acsnano.8b08257 (DOI)000473248300027 ()31083978 (PubMedID)2-s2.0-85066407552 (Scopus ID)
Note

QC 20190820

Available from: 2019-08-20 Created: 2019-08-20 Last updated: 2019-10-29Bibliographically approved
5. Interpenetrated Networks of Nanocellulose and Polyacrylamide with Excellent Mechanical and Absorptive Properties
Open this publication in new window or tab >>Interpenetrated Networks of Nanocellulose and Polyacrylamide with Excellent Mechanical and Absorptive Properties
2018 (English)In: Macromolecular materials and engineering (Print), ISSN 1438-7492, E-ISSN 1439-2054, Vol. 303, no 5, article id 1700594Article in journal (Refereed) Published
Abstract [en]

Composites based on interpenetrating networks (IPNs) of cellulose nanofibril (CNF) aerogels and polyacrylamide are prepared and exhibit robust mechanical, water retaining, and re-swelling capacities. Furthermore, their swelling behavior is not affected by an increased ionic strength of the aqueous phase. These unprecedented IPNs combine the water retaining capacity of the polyacrylamide with the mechanical strength provided by the CNF aerogel template. The CNF aerogel/polyacrylamide composites exhibit a compressive stress at break greater than 250% compared with a neat polyacrylamide hydrogel. Furthermore, the composites retain their wet compression properties after drying and re-swelling, whereas the neat polyacrylamide hydrogels fail at a significantly lower stress and strain after drying and re-swelling. These composite materials highlight the potential of CNF aerogels to strengthen the mechanical properties and reduce the number of fracture defects during the drying and re-swelling of a hydrogel. These composites show the potential of being optimized for a plethora of applications, especially in the hygiene field and for biomedical devices.

Place, publisher, year, edition, pages
Wiley-VCH Verlagsgesellschaft, 2018
Keywords
CNF aerogels, composites, hydrogels, polyacrylamide
National Category
Composite Science and Engineering
Identifiers
urn:nbn:se:kth:diva-228438 (URN)10.1002/mame.201700594 (DOI)000432026700007 ()2-s2.0-85046904921 (Scopus ID)
Funder
Swedish Research Council
Note

QC 20180529

Available from: 2018-05-29 Created: 2018-05-29 Last updated: 2019-10-29Bibliographically approved

Open Access in DiVA

The full text will be freely available from 2020-04-01 10:16
Available from 2020-04-01 10:16

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