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Novel nanocomposite concept based on cross-linking of hyperbranched polymers in reactive cellulose nanopaper templates
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.ORCID iD: 0000-0001-7132-3251
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.ORCID iD: 0000-0001-5818-2378
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. KTH, School of Chemical Science and Engineering (CHE), Centres, Wallenberg Wood Science Center.ORCID iD: 0000-0003-3201-5138
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2011 (English)In: Composites Science And Technology, ISSN 0266-3538, Vol. 71, no 1, 13-17 p.Article in journal (Refereed) Published
Abstract [en]

Cellulosic fibers offer interesting possibilities for good interfacial adhesion due to the high density of hydroxyl groups at the surface. in the present study, the potential of a new nanocomposite concept is investigated, where a porous cellulose nanofiber network is impregnated with a solution of reactive hyperbranched polyester. The polymer is chemically cross-linked to form a solid matrix. The resulting nanocomposite structure is unique. The matrix surrounds a tough nanopaper structure consisting of approximately 20 nm diameter nanofibers with an average interfiber distance of only about 6 nm. The cross-linked polymer matrix shows strongly altered characteristics when it is cross-linked in the confined space within the nanofiber network, including dramatically increased T-g, and this must be due to covalent matrix-nanofiber linkages.

Place, publisher, year, edition, pages
2011. Vol. 71, no 1, 13-17 p.
Keyword [en]
nano composites, fibre/matrix bond, interface, dynamic mechnical thermal analysis
National Category
Chemical Sciences
URN: urn:nbn:se:kth:diva-13488DOI: 10.1016/j.compscitech.2010.09.006ISI: 000285904100003ScopusID: 2-s2.0-78649715826OAI: diva2:325828

QC 20100621. Updated from submitted to published 20120326. Previous title: Novel Nanocomposite Concept based on Hyperbranched Polymers in Reactive Cellulose Nanopaper Templates

Available from: 2010-06-21 Created: 2010-06-21 Last updated: 2012-03-26Bibliographically approved
In thesis
1. Polymer Nanocomposites in Thin Film Applications
Open this publication in new window or tab >>Polymer Nanocomposites in Thin Film Applications
2010 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The introduction of a nanoscopic reinforcing phase to a polymer matrix offers great possibilities of obtaining improved properties, enabling applications outside the boundaries of traditional composites.

The majority of the work in this thesis has been devoted to polymer/clay nanocomposites in coating applications, using the hydroxyl-functional hyperbranched polyester Boltorn® as matrix and montmorillonite clay as nanofiller. Nanocomposites with a high degree of exfoliation were readily prepared using the straightforward solution-intercalation method with water as solvent. Hard and scratch-resistant coatings with preserved flexibility and transparency were obtained, and acrylate functionalization of Boltorn® rendered a UV-curable system with similar property improvements. In order to elucidate the effect of the dendritic architecture on the exfoliation process, a comparative study on the hyperbranched polyester Boltorn® and a linear analogue of this polymer was performed. X-ray diffraction and transmission electron microscopy confirmed the superior efficiency of the hyperbranched polymer in the preparation of this type of nanocomposites.

Additionally, an objective of this thesis was to investigate how cellulose nanofibers can be utilized in high performance polymer nanocomposites. A reactive cellulose “nanopaper” template was combined with a hydrophilic hyperbranched thermoset matrix, resulting in a unique nanocomposite with significantly enhanced properties. Moreover, in order to fully utilize the great potential of cellulose nanofibers as reinforcement in hydrophobic polymer matrices, the hydrophilic surface of cellulose needs to be modified in order to improve the compatibility. For this, a grafting-from approach was explored, using ring-opening polymerization of ε-caprolactone (CL) from microfibrillated cellulose (MFC), resulting in PCL-modified MFC. It was found that the hydrophobicity of the cellulose surfaces increased with longer graft lengths, and that polymer grafting rendered a smoother surface morphology. Subsequently, PCL-grafted MFC film/PCL film bilayer laminates were prepared in order to investigate the interfacial adhesion. Peel tests demonstrated a gradual increase in the interfacial adhesion with increasing graft lengths.

Place, publisher, year, edition, pages
Stockholm: KTH, 2010. 66 p.
Trita-CHE-Report, ISSN 1654-1081 ; 2010:12
Nanocomposites, hyperbranched polymers, montmorillonite, clay nanoparticles, exfoliated, coatings, crosslinking, TEM, XRD, mechanical properties, thermal properties, cellulose nanofibers, Atom Transfer Radical Polymerization, Ring-Opening Polymerization, poly(ε-caprolactone), surface modification, grafting, interfacial adhesion
National Category
Polymer Chemistry
urn:nbn:se:kth:diva-12400 (URN)978-91-7415-615-7 (ISBN)
Public defence
2010-05-07, D1, Lindstedtsvägen 17, KTH, Stockholm, 10:00 (English)
QC20100621Available from: 2010-04-20 Created: 2010-04-16 Last updated: 2012-03-28Bibliographically approved

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Henriksson, MarielleFogelström, LindaBerglund, Lars A.Johansson, Mats K. G.Hult, Anders
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