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Nanobiocomposite Adhesion: Role of Graft Length and Temperature in a Hybrid Biomimetic Approach
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology.
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: 0000-0002-8194-0058
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2013 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 14, no 4, 1003-1009 p.Article in journal (Refereed) Published
Abstract [en]

Cellulose microspheres bearing poly(e-caprolactone) grafts of different molecular weights were investigated to evaluate the effect of graft length on the interfacial properties. Surface force and friction measurements were performed using an atomic force microscope in colloidal probe mode. The maximum interaction distance and adhesion is dependent on the temperature and the time in contact via a diffusion controlled mechanism. The effects are highest for the longer grafts, and molecular weight thresholds were found to lie between 21 and 34 kDa at 25 degrees C and between 9 and 21 kDa at 40 degrees C. The interpenetration of the graft into a matrix leads to "hidden length contributions to adhesion, analogous to those in natural biocomposites. The nanotribology results display Amontonian behavior, and the friction force at zero applied load is higher at the graft graft interface than for a bare cellulose sphere interacting with the graft. These results clearly demonstrate the benefits of the grafted polymer layer on the adhesion, toughness, and resistance nanobiocomposites.

Place, publisher, year, edition, pages
2013. Vol. 14, no 4, 1003-1009 p.
Keyword [en]
Surface Force Measurements, Cellulose Surfaces, Sacrificial Bonds, Friction, Fibers, Xyloglucan, Microscope, Adsorption, Nanoscale, Polymers
National Category
Biochemistry and Molecular Biology Chemical Sciences
URN: urn:nbn:se:kth:diva-122333DOI: 10.1021/bm301790bISI: 000317370500008ScopusID: 2-s2.0-84876008862OAI: diva2:622476
Swedish Foundation for Strategic Research FormasSwedish Research CouncilKnut and Alice Wallenberg Foundation

QC 20130522

Available from: 2013-05-22 Created: 2013-05-20 Last updated: 2014-02-03Bibliographically approved
In thesis
1. Surface Modification of Cellulose by Covalent Grafting and Physical Adsorption
Open this publication in new window or tab >>Surface Modification of Cellulose by Covalent Grafting and Physical Adsorption
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

The interest in new environmentally friendly cellulose‐based productshas increased tremendously over the last years. At the same time theSwedish forest industry faces new challenges in its strive to increase the utilization of cellulose fibers in high‐value end‐products. The aim of this study was to expand the toolbox for surface modification of cellulose byemploying covalent surface‐initiated (SI) polymerizations or by physicaladsorption of polymers. SI‐ring‐opening polymerization (ROP) of ε‐caprolactone (ε‐CL) was performed from filter paper (FP) and high surface area nanopaper (NP).Larger amounts of polycaprolactone (PCL) were grafted from NP, compared to FP, owing to the higher amount of available initiating hydroxyl groups. Furthermore, the mechanical properties of PCL were improved by the grafting of FP and NP, as compared to pure PCL.It is challenging to characterize a polymer grafted from a surface. Hence, quartz crystal microbalance with dissipation (QCM‐D) was employed to investigate SI‐ROP in real time from a cellulose model surface. Furthermore, it was shown by colloidal probe AFM that increased lengthof grafted PCL, from cellulose microspheres, improved the interfacialadhesion to a pure PCL surface, suggesting that chain entanglements havea significant impact on the interfacial properties. Increased temperatureand time in contact also improved the adhesion.In order to investigate the degree of substitution (DS) and the degree of polymerization (DP), PCL‐grafted hydrolyzed cellulose cotton linters (HCCL) were studied by solid state NMR. It was found that despite a DS of only a few percent, the surface character changed considerably; furthermore, the DS was virtually independent of the DP. To increase theamount of grafted polymer, ring‐opening metathesis polymerization (ROMP) of norbornene was performed from FP. Short polymerizationtimes and low temperatures resulted in highly grafted surfaces. Alternatively, physical adsorption by electrostatic interactions was employed to modify a cellulose model surface in the QCM‐D. Cationic latex nanoparticles of poly(dimetylaminoethyl methacrylate‐co‐methacrylicacid)‐block‐poly(methyl methacrylate) were produced by reversible addition‐fragmentation chain‐transfer (RAFT)‐mediated surfactant‐freeemulsion polymerization by polymerization‐induced self‐assembly (PISA).This strategy does not require any organic solvents and could potentiallybe introduced in industrial processes.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2014. 77 p.
TRITA-CHE-Report, ISSN 1654-1081 ; 2014-2
Surface modification, cellulose, covalent modification, physical adsorption, polymer synthesis
National Category
Polymer Technologies
urn:nbn:se:kth:diva-140859 (URN)978-91-7501-987-1 (ISBN)
Public defence
2014-02-21, Kollegiesalen, Brinellvägen 8, KTH, Stockholm, 10:00 (English)
Knut and Alice Wallenberg Foundation, KFCE 8508Formas

QC 20140203

Available from: 2014-02-03 Created: 2014-02-03 Last updated: 2014-02-03Bibliographically approved

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Nordgren, NiklasCarlsson, LinnBlomberg, HannaCarlmark, AnnaMalmström, EvaRutland, Mark W.
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