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Hard and Flexible Nanocomposite Coatings using Nanoclay‐filled Hyperbranched Polymers
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.ORCID iD: 0000-0002-8348-2273
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.ORCID iD: 0000-0003-3201-5138
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology.ORCID iD: 0000-0002-9372-0829
2010 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, Vol. 2, no 6, 1679-1684 p.Article in journal (Refereed) Published
Abstract [en]

The combination of hardness, scratch resistance, and flexibility is a highly desired feature in many coating applications. The aim of this study is to achieve this through the introduction of an unmodified nanoclay, montmorillonite (Na+MMT), in a polymer resin based on the hyperbranched polyester Bottom H30. Smooth and transparent films were prepared from both the neat and the nanoparticle-filled hyperbranched resins. X-ray diffraction (XRD) and transmission electron microscopy (TEM) corroborated a mainly exfoliated structure in the nanocomposite films, which was also supported by results from dynamic mechanical analysis (DMA). Furthermore, DMA measurements showed a 9-16 degrees C increase in Tg and a higher storage modulus above and below the T-g-both indications of a more cross-linked network, for the clay-containing film. Thermogravimetric analysis (TGA) demonstrated the influence of the nanofiller on the thermal properties of the nanocomposites, where a shift upward of the decomposition temperature in oxygen atmosphere is attributed to the improved barrier properties of the nanoparticle-filled materials. Conventional coating characterization methods demonstrated an increase in the surface hardness, scratch resistance and flexibility, with the introduction of clay, and all coatings exhibited excellent chemical resistance and adhesion.

Place, publisher, year, edition, pages
2010. Vol. 2, no 6, 1679-1684 p.
Keyword [en]
nanocomposites, hyperbranched polymers, montmorillonite, coatings, mechanical properties, thermal properties, barrier properties
National Category
Chemical Sciences
URN: urn:nbn:se:kth:diva-13480DOI: 10.1021/am1001986ISI: 000278963600021ScopusID: 2-s2.0-77955494744OAI: diva2:325538
QC20100618. Uppdaterad från Submitted till Published (20101022).Available from: 2010-06-18 Created: 2010-06-18 Last updated: 2010-10-22Bibliographically 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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Fogelström, LindaMalmström, EvaJohansson, MatsHult, Anders
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