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Boujemaoui, A., Ansari, F. & Berglund, L. (2019). Nanostructural Effects in High Cellulose Content Thermoplastic Nanocomposites with a Covalently Grafted Cellulose-Poly(methyl methacrylate) Interface. Paper presented at Symposium on Rational Design of Multifunctional Renewable-Resourced Materials held during the ACS National Meeting, AUG 19-23, 2018, Boston, MA. Biomacromolecules, 20(2), 598-607
Open this publication in new window or tab >>Nanostructural Effects in High Cellulose Content Thermoplastic Nanocomposites with a Covalently Grafted Cellulose-Poly(methyl methacrylate) Interface
2019 (English)In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, no 2, p. 598-607Article in journal (Refereed) Published
Abstract [en]

A critical aspect in materials design of polymer nanocomposites is the nature of the nanoparticle/polymer interface. The present study investigates the effect of manipulation of the interface between cellulose nanofibrils (CNF) and poly(methyl methacrylate) (PMMA) on the optical, thermal, and mechanical properties of the corresponding nanocomposites. The CNF/PMMA interface is altered with a minimum of changes in material composition so that interface effects can be analyzed. The hydroxyl-rich surface of CNF fibrils is exploited to modify the CNF surface via an epoxide-hydroxyl reaction. CNF/PMMA nanocomposites are then prepared with high CNF content (similar to 38 wt %) using an approach where a porous CNF mat is impregnated with monomer or polymer. The nanocomposite interface is controlled by either providing PMMA grafts from the modified CNF surface or by solvent-assisted diffusion of PMMA into a CNF network (native and modified). The high content of CNF fibrils of similar to 6 nm diameter leads to a strong interface and polymer matrix distribution effects. Moisture uptake and mechanical properties are measured at different relative humidity conditions. The nanocomposites with PMMA molecules grafted to cellulose exhibited much higher optical transparency, thermal stability, and hygro-mechanical properties than the control samples. The present modification and preparation strategies are versatile and may be used for cellulose nanocomposites of other compositions, architectures, properties, and functionalities.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2019
National Category
Biochemistry and Molecular Biology
Identifiers
urn:nbn:se:kth:diva-245948 (URN)10.1021/acs.biomac.8b00701 (DOI)000458937200003 ()30047261 (PubMedID)2-s2.0-85050721988 (Scopus ID)
Conference
Symposium on Rational Design of Multifunctional Renewable-Resourced Materials held during the ACS National Meeting, AUG 19-23, 2018, Boston, MA
Note

QC 20190315

Available from: 2019-03-15 Created: 2019-03-15 Last updated: 2019-03-15Bibliographically approved
Kaldéus, T., Larsson, P. T., Boujemaoui, A. & Malmström, E. (2018). One-pot preparation of bi-functional cellulose nanofibrils. Cellulose (London), 25(12), 7031-7042
Open this publication in new window or tab >>One-pot preparation of bi-functional cellulose nanofibrils
2018 (English)In: Cellulose (London), ISSN 0969-0239, E-ISSN 1572-882X, Vol. 25, no 12, p. 7031-7042Article in journal (Refereed) Published
Abstract [en]

Herein, we present a route to obtain bi-functional cellulose nanofibrils (CNF) by a one-pot approach using an already established functionalisation route, carboxymethylation, to which a subsequent functionalisation step, allylation or alkynation, has been added in the same reaction pot, eliminating the need of solvent exchange procedures. The total charge of the fibres and the total surface charge of the nanofibrils were determined by conductometric and polyelectrolyte titration, respectively. Furthermore, the allyl and alkyne functionalised cellulose were reacted with methyl 3-mercaptopropionate and azide-functionalised disperse red, respectively, to estimate the degree of functionalisation. The samples were further assessed by XPS and FT-IR. Physical characteristics were evaluated by CP/MAS C-13-NMR, XRD, AFM and DLS. This new approach of obtaining bi-functionalised CNF allows for a facile and rapid functionalisation of CNF where chemical handles can easily be attached and used for further modification of the fibrils.

Place, publisher, year, edition, pages
SPRINGER, 2018
Keywords
Carboxymethylation, Functionalised cellulose nanofibrils, Allylation, Alkynation
National Category
Paper, Pulp and Fiber Technology
Identifiers
urn:nbn:se:kth:diva-239754 (URN)10.1007/s10570-018-2066-y (DOI)000449946300016 ()2-s2.0-85054565647 (Scopus ID)
Note

QC 20190110

Available from: 2019-01-10 Created: 2019-01-10 Last updated: 2019-02-17Bibliographically approved
Lo Re, G., Spinella, S., Boujemaoui, A., Vilaseca, F., Larsson, P. T., Adås, F. & Berglund, L. (2018). Poly(ε-caprolactone) Biocomposites Based on Acetylated Cellulose Fibers and Wet Compounding for Improved Mechanical Performance. ACS Sustainable Chemistry & Engineering, 5(6), 6753-6760
Open this publication in new window or tab >>Poly(ε-caprolactone) Biocomposites Based on Acetylated Cellulose Fibers and Wet Compounding for Improved Mechanical Performance
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2018 (English)In: ACS Sustainable Chemistry & Engineering, ISSN 2168-0485, Vol. 5, no 6, p. 6753-6760Article in journal, Editorial material (Refereed) Published
Abstract [en]

Poly(epsilon-caprolactone) (PCL) is a ductile thermoplastic, which is biodegradable in the marine environment. Limitations include low strength, petroleum-based origin, and comparably high cost. Cellulose fiber reinforcement is therefore of interest although uniform fiber dispersion is a challenge. In this study, a one-step wet compounding is proposed to validate a sustainable and feasible method to improve the dispersion of the cellulose fibers in hydrophobic polymer matrix as PCL, which showed to be insensitive to the presence of the water during the processing. A comparison between unmodified and acetylated cellulosic wood fibers is made to further assess the net effect of the wet feeding and chemical modification on the biocomposites properties, and the influence of acetylation on fiber structure is reported (ATR-FTIR, XRD). Effects of processing on nano fibrillation, shortening, and dispersion of the cellulose fibers are assessed as well as on PCL molar mass. Mechanical testing, dynamic mechanical thermal analysis, FE-SEM, and X-ray tomography is used to characterize composites. With the addition of 20 wt % cellulosic fibers, the Young's modulus increased from 240 MPa (neat PCL) to 1850 MPa for the biocomposites produced by using the wet feeding strategy, compared to 690 MPa showed for the biocomposites produced using dry feeling. A wet feeding of acetylated cellulosic fibers allowed even a greater increase, with an additional 46% and 248% increase of the ultimate strength and Young's modulus, when compared to wet feeding of the unmodified pulp, respectively.

Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
National Category
Polymer Technologies
Research subject
Chemical Engineering
Identifiers
urn:nbn:se:kth:diva-225425 (URN)10.1021/acssuschemeng.8b00551 (DOI)000431927500117 ()2-s2.0-85046751578 (Scopus ID)
Note

QC 20180531

Available from: 2018-04-04 Created: 2018-04-04 Last updated: 2018-06-04Bibliographically approved
Engström, J., Hatton, F., Boujemaoui, A., Sanchez, C. C., Wågberg, L., D'Agosto, F., . . . Carlmark, A. (2018). Tailored nano-latexes for modification of nanocelluloses: Compatibilizing and plasticizing effects. Paper presented at 255th National Meeting and Exposition of the American-Chemical-Society (ACS) - Nexus of Food, Energy, and Water, MAR 18-22, 2018, New Orleans, LA. Abstract of Papers of the American Chemical Society, 255
Open this publication in new window or tab >>Tailored nano-latexes for modification of nanocelluloses: Compatibilizing and plasticizing effects
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2018 (English)In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 255Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
American Chemical Society (ACS), 2018
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-240157 (URN)000435537702783 ()
Conference
255th National Meeting and Exposition of the American-Chemical-Society (ACS) - Nexus of Food, Energy, and Water, MAR 18-22, 2018, New Orleans, LA
Note

QC 20190111

Available from: 2019-01-11 Created: 2019-01-11 Last updated: 2019-01-11Bibliographically approved
Boujemaoui, A. (2016). Surface Modification of Nanocellulose towards Composite Applications. (Doctoral dissertation). Stockholm: KTH Royal Institute of Technology
Open this publication in new window or tab >>Surface Modification of Nanocellulose towards Composite Applications
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. p. 1, 78
Series
TRITA-CHE-Report, ISSN 1654-1081 ; 2016:12
Keywords
Nanocellulose, surface modification, functionalization, composites
National Category
Polymer Technologies
Research subject
Fibre and Polymer Science
Identifiers
urn:nbn:se:kth:diva-184091 (URN)978-91-7595-888-0 (ISBN)
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: 2017-02-15Bibliographically approved
Mongkhontreerat, S., Andrén, O. C. J., Boujemaoui, A. & Malkoch, M. (2015). Dendritic hydrogels: From exploring various crosslinking chemistries to introducing functions and naturally abundant resources. Journal of Polymer Science Part A: Polymer Chemistry, 53(21), 2431-2439
Open this publication in new window or tab >>Dendritic hydrogels: From exploring various crosslinking chemistries to introducing functions and naturally abundant resources
2015 (English)In: Journal of Polymer Science Part A: Polymer Chemistry, ISSN 0887-624X, E-ISSN 1099-0518, Vol. 53, no 21, p. 2431-2439Article in journal (Refereed) Published
Abstract [en]

Dendritic hydrogels from dendritic-linear-dendritic (DLD) block copolymers based on PEG and bis-MPA dendrons were constructed via UV-initiated thiol-ene, thiol-yne, CuAAC, and amine-NHS crosslinking chemistries. Stoichiometric ratio manipulations, prior to film formation, resulted in functional hydrogels with tuneable compressive moduli. The highest gel fractions for all networks were obtained at off-stoichiometric ratios with surplus of DLDs. Finally, sustainable networks were fabricated by amalgamating DLD, naturally abundant cellulose nanocrystal, and protein-based bovine serum albumin.

National Category
Polymer Chemistry
Identifiers
urn:nbn:se:kth:diva-166862 (URN)10.1002/pola.27750 (DOI)000362372700001 ()2-s2.0-84941803770 (Scopus ID)
Note

Updated from manuscript to article.

QC 20151021

Available from: 2015-05-20 Created: 2015-05-20 Last updated: 2017-12-04Bibliographically approved
Carlmark, A., Boujemaoui, A., Mongkhontreerat, S. & Malmström, E. (2015). Functional cellulose nanocrystals for ATRP and click chemistry-preparation and characterization. Abstract of Papers of the American Chemical Society, 249
Open this publication in new window or tab >>Functional cellulose nanocrystals for ATRP and click chemistry-preparation and characterization
2015 (English)In: Abstract of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 249Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
AMER CHEMICAL SOC, 2015
National Category
Organic Chemistry
Identifiers
urn:nbn:se:kth:diva-243682 (URN)000411183301810 ()
Note

QC 20190305

Available from: 2019-03-05 Created: 2019-03-05 Last updated: 2019-03-05Bibliographically approved
Boujemaoui, A., Mongkhontreerat, S., Malmström, E. & Carlmark, A. (2015). Preparation and characterization of functionalized cellulose nanocrystals. Carbohydrate Polymers, 115, 457-464
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, p. 457-464Article 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
Keywords
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 (Scopus ID)
Note

QC 20150115

Available from: 2015-01-15 Created: 2015-01-07 Last updated: 2017-12-05Bibliographically approved
Larsson, E., Boujemaoui, A., Malmström, E. & Carlmark, A. (2015). Thermoresponsive cryogels reinforced with cellulose nanocrystals. RSC Advances, 5(95), 77643-77650
Open this publication in new window or tab >>Thermoresponsive cryogels reinforced with cellulose nanocrystals
2015 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 5, no 95, p. 77643-77650Article in journal (Refereed) Published
Abstract [en]

Herein, we report the first study of thermoresponsive cryogels with cellulose nanocrystals (CNCs) incorporated into the structure. Free radical polymerization was utilized to synthesize cryogels of poly(N-isopropylacrylamide) (PNIPAAm), resulting in thermoresponsive gels after the cryo-polymerization. Two types of CNCs were investigated: one which had reactive vinyl groups on the surface, enabling covalent incorporation and crosslinking with the cryogel network; and one which had no reactive groups on the surface, rendering it physically embedded in the network. The degree of crosslinking of the cryogels was controlled by varying the addition of N,N'-methylenebisacrylamide (MBAm). The cryogels were analyzed by FE-SEM and were all found to be macroporous. The morphology of the gels was largely dependent on the reaction conditions and the presence of CNC. The swelling properties of the freeze-dried gels were investigated and all gels exhibited a thermoresponsive behavior. Our study showed that the incorporation of CNCs is an effective method to alter both the morphologies and the mechanical properties of a cryogel, although the final properties of the cryogels depend on several different parameters. Due to the complexity of the system, a clear trend regarding the CNC incorporation is difficult to conclude, but compression testing showed that a cryogel having 1 wt% of crosslinkable CNC was far superior to the other gels in terms of mechanical properties, exhibiting that the presence of crosslinkable groups on the surface of CNCs could have a large influence over the final properties.

Place, publisher, year, edition, pages
RSC Publishing, 2015
Keywords
NANOCOMPOSITE HYDROGELS; MECHANICAL STRENGTH; FT-IR; WHISKERS; GELS
National Category
Chemical Sciences
Identifiers
urn:nbn:se:kth:diva-174961 (URN)10.1039/c5ra12603g (DOI)000361559900021 ()2-s2.0-84942033296 (Scopus ID)
Funder
VINNOVA
Note

QC 20151013

Available from: 2015-10-13 Created: 2015-10-09 Last updated: 2017-12-01Bibliographically approved
Boujemaoui, A., Carlsson, L., Malmström, E., Lahcini, M., Berglund, L., Sehaqui, H. & Carlmark, A. (2012). Facile Preparation Route for Nanostructured Composites: Surface-Initiated Ring-Opening Polymerization of epsilon-Caprolactone from High-Surface-Area Nanopaper. ACS Applied Materials and Interfaces, 4(6), 3191-3198
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
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2012 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 4, no 6, p. 3191-3198Article 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
Keywords
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 (Scopus ID)
Note

QC 20160324

Available from: 2012-07-24 Created: 2012-07-23 Last updated: 2017-12-07Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0002-3755-722X

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