Change search
ReferencesLink to record
Permanent link

Direct link
Nanocelluloses - surface modification and use in functional materials
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Biocomposites.
2012 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

Cellulose nanocomposites offer interesting potential in terms of improved properties and new functionalities compared with microcomposites. Preparation from colloidal suspensions is promising, since high reinforcement content is possible and a wide range of constituents can be used. In the first study, the challenge is to form a stable suspension of well-dispersed carbon nanotubes (CNT) and nanofibrillated cellulose (NFC) in water and to prepare commingled high CNT content nanopaper structures by filtration. Various surfactants were used to modify CNT. The NFC was stabilized by charged carboxylate groups. A nonylphenol phosphate ester surfactant, NPPE, worked well for CNT and provided a stable and well-dispersed water suspension of CNT and NFC. Field emission scanning electron microscopy (FE-SEM), porosimetry and atomic force microscopy (AFM) were used to characterize nanopaper structure, and tensile properties were measured as well as surface resistivity. The processing route is water based and it is possible to prepare thin coatings as well as thicker films with a combination of low surface resistivity, flexibility in bending and high strength and toughness in tension.

 As inspired by organo-modified layered silicates, the objective of the second study is to develop an environmentally friendly procedure for the surface modification of cellulose nanocrystals, CNC, using quaternary ammonium salts via adsorption. In order to obtain higher surface charge density on CNC, a new route is developed for preparation of CNC with carboxylic acid groups. Quanternary ammonium cations bearing alkyl, phenyl, glycidyl, and diallyl groups are used to modify CNC to render their surface more hydrophobic. The structure and surface hydrophobicity of unmodified and modified CNC as well as their dispersibility in organic solvent are characterized by AFM, FE-SEM, Fourier-transformed infrared spectroscopy (FT-IR), X-Ray analysis (XDR) and contact angle measurement (CAM). Future work will focus on surface-modified nanocelluloses in composite materials, in order to learn more about surface treatment effects on nanocomposite properties.

Abstract [sv]

Nanokompositer från cellulosa har potential att ge starkt förbättrade egenskaper och ny funktionalitet jämfört med mikrokompositer. De ger även möjlighet till komposittillverkning från kolloidala suspensioner där man kan uppnå hög halt av förstärkningsfasen. Det är också möjligt att välja från en bred flora av lösliga och dispergerbara materialkomponenter. I första studien är utmaningen att skapa en stabil och väldispergerad suspension av kolnanorör (CNT) och nanofibrillerad cellulosa (NFC) i vatten för att genom filtrering framställa nanopapper med interpenetrerande CNT och NFC nätverk. Olika ytaktiva ämnen användes för att modifiera CNT. NFC stabiliserades genom laddade karboxylgrupper på ytan. En nonylfenol fosfatester, NPPE, fungerade bra för CNT och resulterade i en stabil och väldispergerad vattensuspension av CNT och NFC. FE-SEM, densitometri och AFM användes för att karakterisera nanopapperstruktur. Mekaniska egenskaper och ytresistivitet mättes. Processen för framställning av CNT/NFC nanopapper är vattenbaserade och det är möjligt att framställa tunna ytbeläggningar likväl som tjockare filmer. Dessa strukturer har en kombination av låg resistivitet, flexibilitet i böjning liksom hög hållfasthet och seghet i dragbelastning.

 Syftet med den andra studien är att utgå från organo-modifierade skiktade silikater (leror) för att utveckla en miljövänlig ytmodifieringsmetod för nanocellulosa. För att öka ytladdningstätheten på CNC (nanokristaller från cellulosa) utvecklas ett nytt sätt att skapa karboxylgrupper på ytan. Kvarternära ammoniumsalter med alkyl, fenyl, glycidyl och diallylgrupper används för att göra ytan på CNC mer hydrofob. Ytans struktur och hydrofoba karaktär, liksom dispersionsegenskaper i organiska lösningsmedel, karakteriseras med hjälp av AFM, FE-SEM, FT-IR, XDR och kontaktvinkelmätning. Fortsatt arbete kommer att fokusera på ytmodifierad cellulosa i kompositmaterial, för att utveckla förståelsen för effekter av ytmodifiering på nanokompositers egenskaper



Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2012. , 31 p.
Trita-CHE-Report, ISSN 1654-1081 ; 2012:7
Keyword [en]
Nanocellulose, surfactant, surface modification, papermaking process, quaternary ammonium salt
National Category
Polymer Chemistry
URN: urn:nbn:se:kth:diva-90864ISBN: 978-91-7501-255-1OAI: diva2:506963
2012-03-16, Entrénplan, Teknikringen 28, Stockholm, 13:00

QC 20120302

Available from: 2012-03-02 Created: 2012-03-01 Last updated: 2012-09-12Bibliographically approved
List of papers
1. Tough and conductive nanopaper structures, based on cellulose nonofibrils an carbon nanotubes, prepared by processing of aqueous suspensions
Open this publication in new window or tab >>Tough and conductive nanopaper structures, based on cellulose nonofibrils an carbon nanotubes, prepared by processing of aqueous suspensions
(English)Manuscript (preprint) (Other academic)
National Category
Polymer Chemistry
urn:nbn:se:kth:diva-90882 (URN)
QS 2012Available from: 2012-03-02 Created: 2012-03-02 Last updated: 2013-10-16Bibliographically approved
2. Hydrophobic cellulose nanocrystals modified with quaternary ammonium salts
Open this publication in new window or tab >>Hydrophobic cellulose nanocrystals modified with quaternary ammonium salts
2012 (English)In: Journal of Materials Chemistry, ISSN 0959-9428, E-ISSN 1364-5501, Vol. 22, no 37, 19798-19805 p.Article in journal (Refereed) Published
Abstract [en]

An environmentally friendly procedure in aqueous solution for the surface modification of cellulose nanocrystals (CNCs) using quaternary ammonium salts via adsorption is developed as inspired by organomodified layered silicates. CNCs with a high carboxylate content of 1.5 mmol g(-1) were prepared by a new route, direct hydrochloric acid hydrolysis of 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-oxidized nanofibrillated cellulose from a softwood pulp, and characterized by atomic force microscopy (AFM) and X-ray diffraction (XRD). Four quaternary ammonium cation surfactants bearing long alkyl, phenyl, glycidyl, and diallyl groups were successfully used to modify CNCs carrying carboxylic acid groups as characterized by Fourier transform infrared spectroscopy (FTIR). The modified CNCs can be redispersed and individualized in an organic solvent such as toluene as observed by scanning transmission electron microscopy (STEM). One may envision removing excess surfactant to obtain CNC with a monolayer of surfactant. The toluene suspension of the modified CNCs showed strong birefringence under crossed polars but no further chiral- nematic ordering was observed. The model surface prepared by the CNCs modified with quaternary ammonium salts bearing C18 alkyl chains showed a significant increase in water contact angle (71 degrees) compared to that of unmodified CNCs (12 degrees). This new series of modified CNCs can be dried from solvent and have the potential to form well-dispersed nanocomposites with non-polar polymers.

Tempo-Mediated Oxidation, Radical Polymerization, Native Cellulose, Polyelectrolyte Multilayers, Nanocomposite Materials, Surface Oxidation, Organic-Compounds, Whiskers, Adsorption, Fibers
National Category
Polymer Chemistry
urn:nbn:se:kth:diva-90883 (URN)10.1039/c2jm34355j (DOI)000308099900057 ()2-s2.0-84865706683 (ScopusID)
Swedish Research Council

QC 20121109. Updated from manuscript to article in journal.

Available from: 2012-03-02 Created: 2012-03-02 Last updated: 2013-10-16Bibliographically approved

Open Access in DiVA

fulltext(6308 kB)7811 downloads
File information
File name FULLTEXT02.pdfFile size 6308 kBChecksum SHA-512
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Salajková, Michaela
By organisation
Polymer Chemistry

Search outside of DiVA

GoogleGoogle Scholar
Total: 8055 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

Total: 973 hits
ReferencesLink to record
Permanent link

Direct link