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Surface Modification of Nanocellulose towards Composite Applications
KTH, School of Chemical Science and Engineering (CHE), Fibre and Polymer Technology, Coating Technology. 831220-7585. (Coating Technology)ORCID iD: 0000-0002-3755-722X
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Nanocelluloses have attracted great interest during recent decades owing to their renewability, abundancy and remarkable physical and mechanical properties. The aim of this work was to investigate new strategies for surface modification and functionalization of nanocelluloses and their subsequent incorporation in polymer-host matrices.

Nanocomposites of cellulose nanofibrils (CNF) and polycaprolactone (PCL) were produced by employing CNF nanopaper (NP) as a template and surface-initiated ring-opening polymerization (SI-ROP) of ε-caprolactone (ε-CL). SI-ROP of ε-CL from filter paper (FP) was also carried out for comparison. A larger amount of PCL was grafted from NP than from FP. The grafted NP had stronger mechanical properties than neat PCL.

Cellulose nanocrystal (CNC)-reinforced polyvinyl acetate (PVAc) nanocomposites were also investigated. CNC were modified via “SI-reversible addition-fragmentation chain transfer and macromolecular design via the interchange of xanthate” (SI-RAFT/MADIX) polymerization of vinyl acetate (VAc). The resulting nanocomposites exhibited improved mechanical performance than the unmodified CNC.

It is generally agreed that covalent grafting is superior to physical adsorption for the modification of a reinforcing agent. However, this hypothesis has never been thoroughly investigated. CNC was modified either through covalent grafting or through physical adsorption of poly(butyl methacrylate) (PBMA). Both methods resulted in improved mechanical performance than that of pure PCL or PCL containing unmodified CNC. However, covalent grafting gave the best mechanical performance even at high relative humidity.

Functionalized CNC (F-CNC) were obtained through a versatile methodology employing organic acids bearing a functional group were employed for the simultaneous acid hydrolysis and esterification of cellulose fibers. This provided a facile route for the preparation of F-CNC.

Abstract [sv]

Intresset för nanocellulosa har ökat markant under de senaste decennierna eftersom de är förnyelsebara, finns att tillgå i stor mängd, och har mycket bra fysikaliska och mekaniska egenskaper. Syftet med detta arbete var att undersöka nya strategier för ytmodifiering och funktionalisering av nanocellulosa och dess inkorporering i polymera matriser.

Nanokompositer av cellulosa nanofibriller (CNF) och polykaprolakton (PCL) framställdes genom att CNF nanopapper (NP) användes som ett startmaterial från vilken ε-kaprolakton (ε‑CL) polymeriserades med ringöppningspolymerisation (SI-ROP). Som jämförelse ympades även ε-CL från filterpapper (FP) med SI-ROP. Resultatet var att större mängd av polykaprolakton (PCL) ympades från NP jämfört med FP. Det ytmodiferade NP hade bättre mekaniska egenskaper jämfört med ren PCL.

Nanokompositer av cellulosananokristaller (CNC) och polyvinylacetat (PVAc) undersöktes också. CNC modifierades via “SI-reversible addition-fragmentation chain transfer and macromolecular design via the interchange of xanthate” (SI-RAFT/MADIX) polymerisation av vinylacetat (VAc). Nanokompositerna uppvisade bättre mekaniska egenskaper jämfört med omodifierade CNC.

Man har antagit att kovalent ympning är en överlägsen metod för modifiering av ett förstärkande element jämfört med fysikalisk adsorption, men denna hypotes har aldrig undersökts ordentligt. CNC har modifierats endera genom kovalent ympning eller fysikalisk adsorption av poly(butylmetakrylat) (PBMA). Båda metoderna gav förbättrad mekanisk prestanda jämfört med ren PCL och PCL innehållande omodifierad CNC, men kovalent ympning gav bäst prestanda även vid hög relativ fuktighet.

Funktionell CNC (F-CNC) framställdes genom en användbar metod som baseras på organiska syror med en funktionell grupp. F-CNC erhålls genom att hydrolysen av cellulosafibrer utförs genom att använda en kombination av sur hydrolys och förestring. Detta är en enkel och mycket användbar metod för att framställa F-CNC.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2016. , 1, 78 p.
Series
TRITA-CHE-Report, ISSN 1654-1081 ; 2016:12
Keyword [en]
Nanocellulose, surface modification, functionalization, composites
National Category
Polymer Technologies
Research subject
Fibre and Polymer Science
Identifiers
URN: urn:nbn:se:kth:diva-184091ISBN: 978-91-7595-888-0OAI: oai:DiVA.org:kth-184091DiVA: diva2:914128
Public defence
2016-04-22, F3, Lindstedtsvägen 26, KTH, Stockholm, 10:00 (English)
Opponent
Supervisors
Note

QC 20160324

Available from: 2016-03-24 Created: 2016-03-23 Last updated: 2016-04-01Bibliographically approved
List of papers
1. Facile Preparation Route for Nanostructured Composites: Surface-Initiated Ring-Opening Polymerization of epsilon-Caprolactone from High-Surface-Area Nanopaper
Open this publication in new window or tab >>Facile Preparation Route for Nanostructured Composites: Surface-Initiated Ring-Opening Polymerization of epsilon-Caprolactone from High-Surface-Area Nanopaper
Show others...
2012 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 4, no 6, 3191-3198 p.Article in journal (Refereed) Published
Abstract [en]

In this work, highly porous nanopaper, i.e., sheets of papers made from non-aggregated nanofibrillated cellulose (NFC), have been surface-grafted with poly(epsilon-caprolactone) (PCL) by surface-initiated ring-opening polymerization (SI-ROP). The nanopaper has exceptionally high surface area (similar to 300 m(2)/g). The "grafting from" of the nanopapers was compared to "grafting from" of cellulose in the form of filter paper, and in both cases either titanium n-butoxide (Ti(On-Bu)(4)) or tin octoate (Sn(Oct)(2)) was utilized as a catalyst. It was found that a high surface area leads to significantly higher amount of grafted PCL in the substrates when Sn(Oct)2 was utilized as a catalyst. Up to 79 wt % PCL was successfully grafted onto the nanopapers as compared to filter paper where only 2-3 wt % PCL was grafted. However, utilizing Ti(On-Bu)4 this effect was not seen and the grafted amount was essentially similar, irrespectively of surface area. The mechanical properties of the grafted nanopaper proved to be superior to those of pure PCL films, especially at elevated temperatures. The present bottom-up preparation route of NFC-based composites allows high NFC content and provides excellent nanostructural control. This is an important advantage compared with some existing preparation routes where dispersion of the filler in the matrix is challenging.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2012
Keyword
ring-opening polymerization, nanofibrillated cellulose, nanopaper, surface grafting, high surface area
National Category
Nano Technology
Identifiers
urn:nbn:se:kth:diva-99242 (URN)10.1021/am300537h (DOI)000305716900052 ()2-s2.0-84863198035 (ScopusID)
Note

QC 20160324

Available from: 2012-07-24 Created: 2012-07-23 Last updated: 2016-03-24Bibliographically approved
2. RAFT/MADIX Polymerization of Vinyl Acetate on Cellulose Nanocrystals for Nanocomposite Applications
Open this publication in new window or tab >>RAFT/MADIX Polymerization of Vinyl Acetate on Cellulose Nanocrystals for Nanocomposite Applications
(English)Manuscript (preprint) (Other academic)
Keyword
SI-RAFT/MADIX, R-group approach, polyvinyl acetate (PVAc), cellulose nanocrystals (CNC), nanocomposites.
National Category
Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-184106 (URN)
Note

QS 2016

Available from: 2016-03-24 Created: 2016-03-24 Last updated: 2016-03-24Bibliographically approved
3. Polycaprolactone  Nanocomposites Reinforced  with   Cellulose Nanocrystals  Surface - modified  via  Covalent  Grafting  or  Physical Adsorption - a Comparative study
Open this publication in new window or tab >>Polycaprolactone  Nanocomposites Reinforced  with   Cellulose Nanocrystals  Surface - modified  via  Covalent  Grafting  or  Physical Adsorption - a Comparative study
(English)Manuscript (preprint) (Other academic)
Keyword
cellulose nanocrystals, covalent grafting, physical adsorption, reversible-deactivation radical polymerization (RDRP), polycaprolactone (PCL), nanocomposites.
National Category
Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-184107 (URN)
Note

QS 2016

Available from: 2016-03-24 Created: 2016-03-24 Last updated: 2016-03-24Bibliographically approved
4. Preparation and characterization of functionalized cellulose nanocrystals
Open this publication in new window or tab >>Preparation and characterization of functionalized cellulose nanocrystals
2015 (English)In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 115, 457-464 p.Article in journal (Refereed) Published
Abstract [en]

In this work, a series of functional nanocrystals (F-CNCs) was successfully produced by an efficient preparation method, combining acid hydrolysis and Fischer esterification with various organic acids. Functionalities such as ATRP initiators, double bonds, triple bonds, and thiols could be incorporated on CNCs. Surface modification was confirmed by FT-IR, XPS, and elemental analysis. Physical properties of FC-NCs were assessed by AFM, XRD and TGA. Moreover, ATRP initiator functionalized CNCs were utilized to graft poly(methyl methacrylate) via ATRP, thiol functionalized CNCs were reacted with Ellman's reagent to determine the thiol content and dye disperse red 13 was attached to alkyne functionalized CNCs to estimate the propiolate content. The herein presented method is a highly versatile and straightforward procedure for the preparation of F-CNCs which is believed to be a better alternative for the commonly utilized, extensive, multistep, and time consuming post functionalization methods.

Place, publisher, year, edition, pages
Elsevier, 2015
Keyword
Acid hydrolysis, Cellulose nanocrystals, Esterification, Functionalization, Functional organic acid
National Category
Polymer Technologies
Identifiers
urn:nbn:se:kth:diva-158372 (URN)10.1016/j.carbpol.2014.08.110 (DOI)000344869800060 ()2-s2.0-84907484429 (ScopusID)
Note

QC 20150115

Available from: 2015-01-15 Created: 2015-01-07 Last updated: 2016-03-24Bibliographically approved

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