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Thermo-responsive nanofibrillated cellulose by polyelectrolyte adsorption
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.ORCID iD: 0000-0001-9035-4547
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.ORCID iD: 0000-0002-1978-3469
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2013 (English)In: European Polymer Journal, ISSN 0014-3057, E-ISSN 1873-1945, Vol. 49, no 9, p. 2689-2696Article 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.

Place, publisher, year, edition, pages
2013. Vol. 49, no 9, p. 2689-2696
Keywords [en]
Nanofibrillated cellulose (NFC), Polyelectrolyte, Adsorption, Thermoresponsive, Atom transfer radical polymerization (ATRP), Block copolymer
National Category
Polymer Chemistry
Identifiers
URN: urn:nbn:se:kth:diva-129446DOI: 10.1016/j.eurpolymj.2013.05.023ISI: 000323803300032Scopus ID: 2-s2.0-84881369598OAI: oai:DiVA.org:kth-129446DiVA, id: diva2:652866
Funder
Swedish Research CouncilFormas
Note

QC 20131002

Available from: 2013-10-02 Created: 2013-09-30 Last updated: 2018-04-26Bibliographically approved
In thesis
1. Thermoresponsive cellulose-based composites by polymer modification
Open this publication in new window or tab >>Thermoresponsive cellulose-based composites by polymer modification
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. p. 54
Series
TRITA-CHE-Report, ISSN 1654-1081 ; 2015:44
National Category
Polymer Technologies
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-172828 (URN)978-91-7595-654-1 (ISBN)
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
2. Inorganic and organic polymer-grafted nanoparticles: their nanocomposites and characterization
Open this publication in new window or tab >>Inorganic and organic polymer-grafted nanoparticles: their nanocomposites and characterization
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Nanocomposites (NCs) have been widely studied in the past decades due to the promising properties that nanoparticles (NPs) offer to a polymer matrix, such as increased thermal stability and non-linear electrical resistivity. It has also been shown that the interphase between the two components is the key to achieving the desired improvements. In addition, polymer matrices are often hydrophobic while NPs are generally hydrophilic, leading to NP aggregation. To overcome these challenges, NPs can be surface-modified by adding specific molecules and polymers. In the present work, a range of organic and inorganic NPs have been surface-modified with polymers synthesized by atom transfer radical polymerization (ATRP) or surface-initiated ATRP (SI-ATRP).Cellulose nanofibrils (CNF) and cellulose nanocrystals (CNC) are highly crystalline NPs that can potentially increase the Young’s modulus of the NC. In this study, a matrix-free NC was prepared by physisorption of a block-copolymer containing a positively charged (quaternized poly(2-(dimethylamino)ethyl methacrylate), qPDMAEMA) and a thermo-responsive (poly di(ethylene glycol) methyl ether methacrylate, PDEGMA). The modified CNF exhibited a thermo-responsive, reversible behavior. CNCs were polymer-modified either via SI-ATRP or physisorbed with poly (butyl methacrylate) (PBMA) to improve the dispersion and interphase between them and a polycaprolactone (PCL) matrix during extrusion. The mechanical properties of the NCs containing CNC modified via SI-ATRP were superior to the reference and unmodified materials, even at a high relative humidity.Reduced graphene oxide (rGO) and aluminum oxide (Al2O3) are interesting for electrical and electronic applications. However, the matrices used for these applications, such as poly(ethylene-co-butyl acrylate) (EBA) and low density polyethylene (LDPE) are mainly hydrophobic, while the NPs are hydrophilic. rGO was modified via SI-ATRP using different chain lengths of PBMA and subsequently mixed with an EBA matrix. Al2O3 was modified with two lengths of poly(lauryl methacrylate) (PLMA), and added to LDPE prior to extrusion. Agglomeration and dispersion of the NCs were dependent on the lengths and miscibilities of the grafted polymers and the matrices. rGO-EBA NCs showed non-linear direct current (DC) resistivity upon modification, as the NP dispersion improved with increasing PBMA length. Al2O3-LDPE systems improved the mechanical properties of the NCs when low amounts of NPs (0.5 to 1 wt%) were added, while decreasing power dissipation on the material.Finally, PLMA-grafted NPs with high polymer quantities and two grafting densities in Al2O3 and silicon oxide (SiO2) nanoparticles were synthesized by de-attaching some of the silane groups from the surfaces, either by hydrolysis or by a mild tetrabutylammonium fluoride (TBAF) cleavage. These compounds were characterized and compared to the bulk PLMA, and were found to have very interesting thermal properties.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2018. p. 71
Series
TRITA-CBH-FOU ; 2018:15
Keywords
Si-ATRP, ATRP, polyelectrolytes, rGO, aluminium oxide, silica, CNF, CNC, PCL, LDPE, EBA, nanocomposites, matrix-free, extrusion
National Category
Polymer Technologies
Research subject
Fibre and Polymer Science
Identifiers
urn:nbn:se:kth:diva-226888 (URN)978-91-7729-752-9 (ISBN)
Public defence
2018-05-25, F3, Lindstedtsvägen 26, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20180427

Available from: 2018-04-27 Created: 2018-04-26 Last updated: 2018-04-27Bibliographically approved

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