Char-forming behavior of nanofibrillated cellulose treated ...
Microscopic Characterization of Nanofibrillated Cellulose - Inorganic Nanoparticle Hybrid Systems
1
Experimental Microscopic Characterization of Nanofibrillated Cellulose- Inorganic Nanoparticle Hybrid Systems J. Hidalgo 1,3 , S. Peresin 2 , G. Kortaberria 3 and A. Tejado 1 1 Tecnalia Research & Innovation , Area Anardi 5, Azpeitia, Spain 2 VTT-Technical Research Centre, Biologinkuja 3, Espoo, Finland 3 University of the Basque Country, Plaza Europa 1, Donostia-San Sebastian, Spain Objective The last decade have witnessed an increasing interest in biobased organic-inorganic hybrid materials, where properties of each component are combined giving remarkable characteristics. However, some of the basic parameters which dominate the formation of such materials are still unclear. In this work, we develop and characterize new organic-inorganic hybrids made of micro/nano fibrillated cellulose (MFC/NFC) and inorganic nanoparticles (NP), trying to better understand the fundamentals operating behind the assembling of the different constituents. Three cellulose types, i.e. MFC, NFC and dicarboxylated cellulose fibres (DCC), were combined with three inorganic NP: titanium dioxide (TiO 2 ), sodium montmorillonite (MMT) and organically modified montmorillonite (OMMT). Atomic Force Microscopy (AFM) and Field Emission Scanning Electron Microscopy (FE-SEM) were employed to study the topology of such nanocomposites prepared by either casting or spin coating. Inorganic Nanoparticles OMMT MMT TiO 2 Organic Substrates NFC MFC DCC Acknowledgements Cost Action FP1105, for funding this research in the frame of a Short Time Scientiffic Mission (STSM). VTT (High Performance Fibre Products Group) and Aalto University for helping with AFM and SEM analysis. Cellulose preparation Homogenizer 3 times 400m + 5 times 200m MFC Z-shaped interaction chamber. Microfluidics Inc., USA Mechanical treatment Periodate oxidation Chlorite oxidation DCC Di carboxylated cellulose chains Chemical treatment TEMPO oxidation Homogenizer NFC (2,2,6,6-Tetramethyl-piperidin-1-yl)oxyl TEMPO radical MFC Chemo-mechanical treatment 5 times 200m + 5 times 100m + + + Mixing 1wt% 1wt% MFC/NFC NP Casting on polystyrene dish Spin coating + Pt sputtering Ultrasonication Hybrid preparation Conclusions Stability of suspensions was evaluated and correlated with the quality of the films formed via casting or vacuum filtration. Remarkably, while MMT always gives rise to stable suspensions and good quality films, TiO 2 causes severe flocculation of NFC and DCC, showing identical behaviour to OMMT. Microscopic analyses confirm those floc promoting interactions and succeed in characterizing different features of the samples, such as the well- defined profile height differences, the disintegrating effect of sonication on DCC sample and the homogeneous nanoparticle layer of OMMT on MFC substrate. NFC/OMMT MFC/MMT Preliminary assessments Film Formation by casting Hybrids Suspension Stability Charge Interaction with NP Stability of suspensions Filmability Key parameter: Anionic charge density of cellulosic substrates DCC NFC MFC MFC NFC DCC MMT MFC NFC DCC OMMT MFC NFC DCC MFC NFC DCC Settling TiO 2 MFC NFC DCC MFC NFC DCC Settling bad film AFM Images Linear height profiles extracted from AFM images According to roughness results some appreciations can be made: NFC ( ≈100nm) is more fibrillated and smoother than MFC ( ≈200nm), but DCC ( ≈50nm) is the smoothest cellulose sample. MMT-containing hybrids show almost identical roughness ( ≈200nm) regardless the type of cellulose substrate. The MFC/OMMT hybrid has a very flat and regular surface ( ≈ 10nm). Strong aggregation is observed when comparing TiO 2 NP (particle size≈21nm) and MFC/TiO 2 hybrids ( ≈ 400nm). good film Cellulosic substrates MFC Hybrids SEM Images 1 μm 1)Bundles of fibrils. 2)Uniform surface of thin fibrils. 3)One big cellulose fibre breaking in smaller fibrils. 4)Surface looks to be empty at lower magnification level. Only previous shown fibrillated fragments are observed. 5)At higher magnification, nanosized fibrils can be clearly seen covering the whole surface. 10 μm Different roughness of the samples is already visible: big fibrils of MFC, MMT aggregates and softer surface on NFC and DCC. The surface of fibrils is covered by a layer of clay. Best hybrid films (MFC) Cellulosic substrates 10 μm 10 μm 50 μm 1 μm 50 μm 50 μm 50 μm 1 μm 1 μm Most Settled Suspensions (Study of aggregates) Huge nanoclay aggregates, some fully and others partially covered by a layer of nanofibrils. 5 μm 25 μm 1 μm TiO 2 particles are uniformly dispersed. With a higher magnification level, in NFC/TiO 2 hybrid all NP are fully covered by fibrils. On the other hand, DCC/TiO 2 hybrid has uncovered nanoparticles (sharp edges can be seen). That explains the settling of NFC/TiO 2 suspension totally, and the cloudy upper part of the DCC/TiO 2 revealing a weaker interaction between NP and cellulose nanofibrils. 5 μm 5 μm 100 nm 100 nm 250 nm
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Transcript of Microscopic Characterization of Nanofibrillated Cellulose - Inorganic Nanoparticle Hybrid Systems
Experimental
Microscopic Characterization of Nanofibrillated Cellulose-Inorganic Nanoparticle Hybrid Systems
J. Hidalgo1,3, S. Peresin2, G. Kortaberria3 and A. Tejado1
1 Tecnalia Research & Innovation , Area Anardi 5, Azpeitia, Spain2 VTT-Technical Research Centre, Biologinkuja 3, Espoo, Finland
3 University of the Basque Country, Plaza Europa 1, Donostia-San Sebastian, Spain
Objective The last decade have witnessed an increasing interest in biobased organic-inorganic hybrid materials, where properties of each component arecombined giving remarkable characteristics. However, some of the basic parameters which dominate the formation of such materials are still unclear. In thiswork, we develop and characterize new organic-inorganic hybrids made of micro/nano fibrillated cellulose (MFC/NFC) and inorganic nanoparticles (NP),trying to better understand the fundamentals operating behind the assembling of the different constituents.
Three cellulose types, i.e. MFC, NFC and dicarboxylated cellulose fibres(DCC), were combined with three inorganic NP: titanium dioxide (TiO2),sodium montmorillonite (MMT) and organically modified montmorillonite(OMMT). Atomic Force Microscopy (AFM) and Field Emission ScanningElectron Microscopy (FE-SEM) were employed to study the topology ofsuch nanocomposites prepared by either casting or spin coating.
Inorganic Nanoparticles
OMMTMMT TiO2
Organic Substrates
NFCMFC DCC
Acknowledgements Cost Action FP1105, for funding this research in the frame of a Short Time Scientiffic Mission (STSM).VTT (High Performance Fibre Products Group) and Aalto University for helping with AFM and SEM analysis.
Cel
lulo
se p
repa
ratio
n
Homogenizer3 times 400m
+ 5 times 200m
MFC
Z-shaped interaction chamber.Microfluidics Inc., USA
Mechanical treatment
Periodate oxidation
Chlorite oxidation
DCC
Di carboxylated cellulose chains
Chemical treatment
TEMPO oxidation
Homogenizer
NFC
(2,2,6,6-Tetramethyl-piperidin-1-yl)oxylTEMPO radical
MFC
Chemo-mechanical treatment
5 times 200m+
5 times 100m
++ +
Mixing
1wt%1wt%
MFC/NFC NP
Casting on polystyrene dish
Spin coating + Pt sputtering
Ultr
ason
icat
ion
Hyb
rid
prep
arat
ion
Conclusions Stability of suspensions was evaluated and correlated with the quality of the films formed via casting or vacuum filtration. Remarkably,while MMT always gives rise to stable suspensions and good quality films, TiO2 causes severe flocculation of NFC and DCC, showing identical behaviour toOMMT. Microscopic analyses confirm those floc promoting interactions and succeed in characterizing different features of the samples, such as the well-defined profile height differences, the disintegrating effect of sonication on DCC sample and the homogeneous nanoparticle layer of OMMT on MFC substrate.
NFC/OMMT
MFC/MMT
Preliminary assessments
Film Formation by casting
Hybrids
Suspension Stability Charge Interaction with NP Stability of suspensions Filmability
Key parameter: Anionic charge density of cellulosic substratesDCC NFC MFC
MFC NFC DCC
MMT
MFC NFC DCC
OMMT
MFC NFC DCC
MFC NFC DCC
Settling
TiO2
MFC NFC DCC
MFC NFC DCC
Settling
bad film
AFM Images Linear height profiles extracted from AFM images
According to roughness results some appreciations can be made: NFC ( ≈100nm) is more fibrillated and smoother than MFC ( ≈200nm),
but DCC ( ≈50nm) is the smoothest cellulose sample. MMT-containing hybrids show almost identical roughness ( ≈200nm)
regardless the type of cellulose substrate. The MFC/OMMT hybrid has a very flat and regular surface ( ≈ 10nm). Strong aggregation is observed when comparing TiO2 NP (particle size≈21nm)
and MFC/TiO2 hybrids ( ≈ 400nm).
good film
Cel
lulo
sic
subs
trat
esM
FC
Hyb
rids
SEM Images
1 µm
1)Bundles of fibrils.2)Uniform surface of thin fibrils.3)One big cellulose fibre breaking insmaller fibrils.4)Surface looks to be empty at lowermagnification level. Only previousshown fibrillated fragments are observed.5)At higher magnification, nanosizedfibrils can be clearly seen covering thewhole surface.
10 µm
Different roughness of the samples is already visible: big fibrils of MFC, MMT aggregates and softer surface on NFC and DCC. The surface of fibrils is covered by a layer of clay.
Best hybrid films (MFC)
Cellulosic substrates
10 µm 10 µm
50 µm
1 µm
50 µm50 µm50 µm
1 µm 1 µm
Most Settled Suspensions (Study of aggregates)
Huge nanoclay aggregates, some fully and others partially covered by a layer of nanofibrils.
5 µm
25 µm
1 µm
TiO2 particles are uniformly dispersed.With a higher magnification level, in NFC/TiO2 hybrid all NP are fully covered by fibrils. On theother hand, DCC/TiO2 hybrid has uncovered nanoparticles (sharp edges can be seen). That explainsthe settling of NFC/TiO2 suspension totally, and the cloudy upper part of the DCC/TiO2 revealing aweaker interaction between NP and cellulose nanofibrils.
5 µm 5 µm
100 nm 100 nm
250 nm
