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Thermoresponsive cellulose-based composites by polymer modification
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The interest in utilizing cellulose based materials has grown rapidly in recent years, due to the growing environmental concerns about utilizing fossil based material. One potential application of cellulose is in thermoresponsive materials, which are attracting attention due to their ability of altering conformation when exposed to changes in external temperature. In this study, a variation of cellulose substrates have been utilized; both as the main component and as reinforcing fillers in thermoresponsive composites.

Photoinduced controlled radical polymerization was utilized to graft the thermoresponsive polymer poly(di(ethylene glycol) ethyl ether acrylate) (PDEGA)  from the surface of filter paper. The method showed to be efficient to graft large amounts of polymer from the cellulose surface in short reaction times, while utilizing smaller amounts of catalyst than typically employed in controlled radical polymerizations.

Di-, tri, and star block copolymers of quaternized poly(2-(dimethylamino)ethyl methacrylate) (qPDMAEMA) and poly(di(ethylene glycol) methyl ether methacrylate) (PDEGMA) were synthesized by atom transfer radical polymerization (ATRP), and adsorbed to cellulose nanofibrils (CNFs) in a water dispersion. This provided a simple route for the preparation of thermoresponsive CNF based composites.

Thermoresponsive cryogels of poly(N-isopropylacrylamide) (PNIPAAm), synthesized by free radical polymerization (FRP), were reinforced by the addition of cellulose nanocrystals (CNCs). Two types of CNCs were investigated: neat CNC and CNC with acrylic, polymerizable,  groups attached to its structure. The CNC addition showed to be an efficient way to modify the mechanical properties of the cryogels.

All materials synthesized in this project displayed thermoresponsive properties. Cellulose can therefore be considered to be a promising material for the production of more environmentally friendly thermoresponsive composites.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2015. , 54 p.
Series
TRITA-CHE-Report, ISSN 1654-1081 ; 2015:44
National Category
Polymer Technologies
Research subject
Chemical Engineering
Identifiers
URN: urn:nbn:se:kth:diva-172828ISBN: 978-91-7595-654-1 (print)OAI: oai:DiVA.org:kth-172828DiVA: diva2:849867
Public defence
2015-09-25, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20150902

Available from: 2015-09-02 Created: 2015-08-31 Last updated: 2017-02-22Bibliographically approved
List of papers
1. Cellulose grafting by photoinduced controlled radical polymerisation
Open this publication in new window or tab >>Cellulose grafting by photoinduced controlled radical polymerisation
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2015 (English)In: Polymer Chemistry, ISSN 1759-9954, E-ISSN 1759-9962, Vol. 6, no 10, 1865-1874 p.Article in journal (Refereed) Published
Abstract [en]

The photoinduced controlled radical polymerisation (CRP) technique has been utilised to graft methyl acrylate (MA) and di(ethylene glycol) ethyl ether acrylate (DEGA) from filter paper. Grafting of MA was performed from alpha-bromoisobutyryl bromide functionalised papers. The amount of polymer grafted on the surface could be regulated by modifying the target DP of the reaction. SEC of cleaved linear polymer grafts showed that the grafting from filter papers proceeded with different kinetics compared to polymerisation from a free initiator added to the reaction mixture, resulting in higher dispersity. Furthermore, filter papers were polymerised with a-chloro-epsilon-caprolactone by surface-initiated ring opening polymerisation, yielding linear grafts containing initiating functions through-out the main chain. This functionality was subsequently utilised for the photoinduced CRP grafting of DEGA, yielding a graft-on-graft structure, which resulted in a thermoresponsive cellulose surface.

National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-164011 (URN)10.1039/c4py01618a (DOI)000350641400021 ()2-s2.0-84923913852 (Scopus ID)
Note

QC 20150423

Available from: 2015-04-23 Created: 2015-04-13 Last updated: 2017-12-04Bibliographically approved
2. Thermo-responsive nanofibrillated cellulose by polyelectrolyte adsorption
Open this publication in new window or tab >>Thermo-responsive nanofibrillated cellulose by polyelectrolyte adsorption
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2013 (English)In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 49, no 9, 2689-2696 p.Article in journal (Refereed) Published
Abstract [en]

In this study, thermo-responsive nanofibrillated cellulose (NFC) has been produced by the adsorption of thermo-responsive polyelectrolytes to the NFC. Three block copolymers were synthesized in which the polyelectrolyte block was composed of quaternized poly(2-(dimethylamino)ethyl methacrylate) (qPDMAEMA) and the thermo-responsive block was composed of poly(di(ethylene glycol) methyl ether methacrylate) (PDEGMA). The block copolymers were synthesized employing atom transfer radical polymerization (ATRP) and the PDMAEMA block was utilized as a macroinitiator for the polymerizations of PDEGMA. The length and charge of the PDMAEMA block were kept constant in all three block copolymers, while three different molecular weights of the PDEGMA block was synthesized. The PDMAEMA block was quaternized to introduce positive charges and the block copolymers were subsequently adsorbed onto the negatively charged NFC that was dispersed in water. The lower critical solution temperatures (LCSTs) of the free block copolymers in solution were analyzed by dynamic light scattering (DLS). The composites were analyzed by QCM-D, FT-IR and TGA, which clearly showed an adsorption of the block copolymer onto the NFC. The grafted NFC showed a thermo-responsive behavior in solution upon heating and cooling, thus supporting that the properties of the polyelectrolyte can be transferred to the cellulose. By this methodology, thermo-responsive NFC materials can be produced in a straight-forward manner in water dispersions, without performing any chemical reactions on the NFC.

Keyword
Nanofibrillated cellulose (NFC), Polyelectrolyte, Adsorption, Thermoresponsive, Atom transfer radical polymerization (ATRP), Block copolymer
National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-129446 (URN)10.1016/j.eurpolymj.2013.05.023 (DOI)000323803300032 ()2-s2.0-84881369598 (Scopus ID)
Funder
Swedish Research CouncilFormas
Note

QC 20131002

Available from: 2013-10-02 Created: 2013-09-30 Last updated: 2017-12-06Bibliographically approved
3. Thermoresponsive hydrogels of cellulose nanofibrils and triblock copolymers
Open this publication in new window or tab >>Thermoresponsive hydrogels of cellulose nanofibrils and triblock copolymers
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(English)Manuscript (preprint) (Other academic)
Abstract [en]

Atom transfer radical polymerization (ATRP) has been utilized to synthesize triblock and star-block copolymers of quaternized poly(2-(dimethylamino)ethyl methacrylate) (qPDMAEMA) and poly(di(ethylene glycol) methyl ether methacrylate (PDEGMA). The block copolymers, that all contained a minimum of two charged blocks, were sequential adsorbed to negatively charged cellulose nanofibrils (CNF) in dilute water suspension, forming thermoresponsive hydrogels. The presence of more than one charge block allowed for the polymers to form permanent, physically crosslinked, gels when adsorbed to the CNF. The ability of the polymers to adsorb to CNF was confirmed by quartz crystal microbalance with dissipation monitoring (QCM-D), and the thermoresponsive properties of the gels were investigated by rheological measurements and gravimetric measurements. This method was shown to be promising for the facile, production of thermoresponsive hydrogels composed of CNF.

National Category
Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-172930 (URN)
Note

QS 2015

Available from: 2015-09-02 Created: 2015-09-02 Last updated: 2015-09-02Bibliographically approved
4. Thermoresponsive cryogels reinforced with cellulose nanocrystals
Open this publication in new window or tab >>Thermoresponsive cryogels reinforced with cellulose nanocrystals
(English)Manuscript (preprint) (Other academic)
Abstract [en]

Herein, we report the first study of thermoresponsive cryogels with cellulose nanocrystals (CNCs) incorporated into the structure. Free radical polymerization was utilized to synthesize cryogels of poly(N-isopropylacrylamide) (PNIPAAm), resulting in thermoresponsive gels after the cryo-polymerization. Two types of CNCs were investigated: one which had reactive vinyl groups on the surface, enabling covalent incorporation and crosslinking with the cryogel network; and one which had no reactive groups on the surface, rendering it physically embedded in the network. The degree of crosslinking of the cryogels was controlled by varying the addition of N,N´-methylenebisacrylamide (MBAm). The cryogels were analyzed by FE-SEM and were all found to be macroporous. The morphology of the gels was largely dependent on the reaction conditions and the presence of CNC. The swelling properties of the freeze-dried gels were investigated and all gels exhibited a thermoresponsive behavior. Our study showed that the incorporation of CNCs is an effective method to alter both the morphologies and the mechanical properties of a cryogel, although the final properties of the cryogels depend on several different parameters. Due to the complexity of the system, a clear trend regarding the CNC incorporation is difficult to conclude, but compression testing showed that a cryogel having 1 wt% of crosslinkable CNC was far superior to the other gels in terms of mechanical properties, exhibiting that the presence of crosslinkable groups on the surface of CNCs could have a large influence over the final properties.

National Category
Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-172931 (URN)
Note

QS 2015

Available from: 2015-09-02 Created: 2015-09-02 Last updated: 2015-09-02Bibliographically approved

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