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New perspectives for the application of cellulose nanofibers as building blocks in functional materials
Tanja Zimmermann Head of Applied Wood Materials Lab Functional Cellulose Materials Empa Materials Science and Technology, Switzerland
Zheng et al., Empa 2014
Sehaqui et al., Empa, 2014 Siqueira et al., Empa, 2015
Final Meeting COST FP1205, KTH Stockholm
Motivation for use of Cellulose Nanofibers (CNF)
• Lightweight material, builds network structures • Renewable resource, biodegradable • High strength and stiffness • water storage capacity, rheology modifier • High surface area and aspect ratio • High reactivity, barrier properties
Translucent films (Nogi, 2009)
Porous material (porosity ~ 99%)
Powder (Eyholzer, 2010) Transparent gel (1.5 % w/w)
Chemical functionalization of CNF
- Controlled modification (esp. esterification, etherification, condensations)
- Impact of the modification on the materials’ properties: thermal stability, crystallinity, dispersion in organic solvents, wettability, etc…
Chemistry as a powerful « toolbox » to decorate nanocelluloses and expand their application fields
- Modification of starting material, single nanofibers, films, foams
Time (min)
DS
Functionalized nanofibers Functionalized films Functionalized foams
Research interest in nanocelluloses in Europe
1 cm
water
dodecane
Research interest increased within the last 10 to 15 years enormously – number of SCI papers from about 50 in 2004 to far more than 1000 in 2016
Compared to US and Canada more research on fibrillated cellulose than on cellulose nanocrystals
Up-scaling activities at industrial scale especially in Scandinavia (e.g. Borregaard, Stora Enso, UPM,…) using grinding or homogenization technologies, new also in Switzerland (Wicor Weidmann)
Various pre-treatments (TEMPO-oxidation, enzymatical treatment, etc.)
Main Applications in Coatings, films, functional (nano)papers, barrier papers Composites Packaging Purification / separation technologies Hydrogels and Aerogels ….
Research interests and application examples of CNF at Empa
CNF-based functional materials
Health and performance, superabsorbents, sensors
(CNF in hydrogels)
Nanostructured materials, Composites (nanopapers, CNF (composite) films)
Energy, Sustainable Built Environment
(CNF foams/ aerogels)
Natural resources and pollutants (CNF membranes/ foams/ aerogels)
1 cm
water
dodecane
Health and performance, superabsorbents, sensors
Collaboration PhD thesis Ramon Weishaupt, Empa St. Gallen (Lab of Katharina Maniura) Weishaupt et al. 2015. Biomacromolecules
NFC as high capacity carrier for proteins and peptides
7
Schematic view of two-step reaction for the covalent immobilization of adsorbed biomolecules to oxidized-NFC.
Biomedical sensor applications
8
The sensing cyanobacterial biomolecule C-phycocyanin (CPC) was genetically engineered and integrated into NFC films as carrier material.
CPC-CNF films as biosensors for the detection of free copper ions in human blood serum (heavy metal sensitive fluoreszent emission).
Collaboration PhD thesis Ramon Weishaupt, Empa St. Gallen Weishaupt et al. 2017. Adv. Func. Mat.
Nanostructured Materials, Composites
Direct ink writing («3-D-Printing») Coating applications
Direct ink writing using Cellulose Nanocrystals
Empa Center for X-ray Analytics Complex Materials - ETH Zürich Lewis group – Harvard University
Direct ink writing (DIW) technique as powerful extrusion based technique for fabrication of 3D microstructures.
Rod-like shape CNC: average lengths of 120 nm ± 35 nm and diameters of 6.5 nm ± 2.2 nm.
We optimised a CNC water-based highly concentrated ink (20 wt%) in terms of viscoelastic properties Yield stress 349 Pa, storage modulus G’ > loss modulus G’’
Work of Dr. Gilberto Siqueira
3D Printing of Cellulose Crystals (CNC) ordered structures
Empa Center for X-ray Analytics Complex Materials - ETH Zürich Lewis group – Harvard University
3D printed structures of all cellulose-based composites.
a) Photograph of 3D printed filaments composed of 16 layers. b, c) AFM (b) phase and (c) height images of the 3D printed filaments’ surfaces. d) Drawings representing the CNC 3D printed filaments.
a b c
d e
Siqueira et al. 2017. Advanced Funct. Materials
Degree of orientation up to 84 % (calculated from 2 D-WAXS measurements
Work of Dr. Gilberto Siqueira
Composites: Transparency by UV spectroscopy
Chemical modification of CNC: more transparent composites.
Modified material CNC composite: transmittance ~ 92%
Unmodified CNC composite: transmittance ~ 80%.
(inks contained HEMA monomer (hydroxyethyl methacrylate), PUA oligomer (polyether urethane acrylate), photoinitiator and 10 wt% non-modified or acetylated CNC)
Mechanical properties of polymer composites
Stiff and Brittle (M1) Soft and Rubbery (M2) Matrices:
Enhanced mechanical properties of composites.
Differences between composites tested in the longitudinal and transverse directions.
CNF composite films for wood coating applications • Use CNF to modify mechanical / physical properties of wood coatings
Fungal growth
Haildamage
Photodegradation
Cracking
30 µm
CNF for reinforcement
Ols
son
et a
l 201
1 N
atur
e N
T
0.4 µm
CNF as carrier material
functionalization with nanoparticles and organic components UV-absorber/Zinc oxide, HALS; biocides
PhD thesis Franziska Grueneberger Grueneberger et al. 2014. Cellulose Grueneberger et al. 2014. J. Mater. Sci. Grueneberger et al. 2015. Prog. Org. Coat. Grueneberger et al. 2016. Colloid and Polymer Science
Unmodified CNF can act as multifunctional wood coating additive, that is compatible to different tested acrylic and alkyd resins.
CNF act as conventional thickener and rheological modifier, since the viscosity and flow behavior of the coating is strongly dependent on the NFC content.
CNF can act as carrier and dispersing agent for various wood protecting compounds such as nanoparticles, UV-absorber or biocides.
CNF influence the film formation and reduce undesired crack formation in brittle coating films.
CNF have a great potential as novel multifunctional additive
Vision Wood Module, www.nest.empa.ch
Natural resources and pollutants
CNF membranes, filters, foams, and aerogels for depollution
CNF in environmental remediation
Functions: COO-: carboxylate N+:trimethyl ammonium C: carbon (pyrolysis)
Contaminants: M+: Heavy metal ions NOM: Natural organic matter (humic acid) NPs: Nanoparticles A-: anions (nitrate, phosphate, sulfate and fluoride)
Work of Dr. Houssine Sehaqui
5 10 15 20 25 30 35 40
2
Inte
nsity
CI
5 10 15 20 25 30 35 40
2
Inte
nsity
CI
5 10 15 20 25 30 35 40
2
Inte
nsity
CI
SEM
XR
DTE
M
WCNF BCNF ACNF
Stefelova, J. et al. (2017) ACS Sustainable Chemistry & Engineering
CNF pyrolysis
CNF can be pyrolysed leading to a carbon-rich material (char) for non-polar species absorption/adsorption.
Wood, bacteria and algae CNF
Structure
• The structure of the char ressembles the structure of the CNF substrate.
HD: heat drying SCD: super critical drying BuFD: tert-butanol freeze-drying
10 100 100010 100 10000
50
100
10 100 1000 10 100 1000
0
30
60
90 Acetone
ChloroformEthanol Toluene Dodecane
Silicone oilMineral oilMotor oil
10 100 1000(kg m-3)
10 100 10000
50
100
(kg m-3)
Upt
ake
(g g
-1)
10 100 1000(kg m-3)
10 100 1000(kg m-3)
0
30
60
90
0
30
60
90
Upt
ake
(g g
-1)
a
a
b
Oil/solvents absorption
• Low density (high porosity) CNF prepared via freeze-drying gives chars with a good oil/solvent absorption capacity (up to 118 g/g).
• Char from bacterial cellulose gives best absorption performance optimum oleophilicity, mechanical properties and pores characteristics.
Black, green, and red indicate WCNF, BCNF, and ACNF Uptake weight versus density of substrate
Dyes adsorption
Ref AD FD BuFD SCD
Methylene blue =410 mg L-1 Crystal violet Congo red
Ref Ref BuFD BuFD
f
15 min 2 hours 1 day 10 days0
20
40
60
80
100
% R
emov
al
HDFDSCDBuFD
• The drying method of CNF affects the adsorption properties of the chars. Best performance for high surface area chars from supercritical CO2 drying of CNF.
15 m
in
120
min
400
min
1 da
y
3 da
ys
10 d
ays
1 m
onth
0
20
40
60
80
% R
emov
al
WCNF charBCNF charACNF char
• For the same drying method, CNF with high crystallinity (from algae) gives chars with higher adsorption capacity.
HDCNF
Energy, Sustainable Built Environment
NFC foams for gas capture
and insulation
Ambient air
CO2 capture
CO2-free air
Pure CO2 release
Low grade heat, e.g. solar heat
Gebert Rüf, ETH spin-off Climeworks LLC, ETH Zürich, Professorship of Renewable Energy Carriers PhD thesis Christoph Gebald
Aerogels/ Foams for gas capture
Stability of CO2 capture capacity over 100 sorption/desorption cycles
Gebald et al. 2011. Patent application Gebald et al. 2011, 2013, 2014 Env. Science and Technology
Use of CO2 for greenhouses, carbonisation of beverages, synfuels…..
Professorship of Renewable Energy Carriers
Aerogels/ Foams for gas capture
Sehaqui et al. 2015. Env. Science and Technology .
PEI-19 PEI-31 PEI-44 PEI-52 PEI-620
0.5
1
1.5
2
2.5
CO
2 cap
acity
(mm
ol/g
)
1 2 3 54
1 2 3 54
1 2 3 54 12
3 541
23
54
Evolution of the CO2 adsorption capacity over 5 consecutive DAC cycles for the CNF/PEI sorbents. Cycle number on top of each bar.
Oxidized CNF and high molar mass polyethylenimine (PEI), foam via freeze-drying Porosity >97 %, specific surface area 2.7 – 8.3 m2/g
Super insulating hybrid materials
Cellulose structure totally covered with silica
SiO2 + silylated scaffold Possible to reinforce super-insulating silica aerogels with 3D organic nanocellulose scaffold
Silylation promotes the adhesion between the organic scaffold and the mesoporous silica network
Super-insulating hybrid materials (l ≤ 20 mW/m·K)
Zhao et al. 2015. Adv. Funct. Mater. Collaboration with the groups of Dr. Matthias Koebel, Dr. Philippe Tingaut, Prof. G. Sèbe, Univ. Bordeaux
SiO
O
OH
OSi
OO
O
O SiO
OHO
Si O Si
HO
O
Si OO
Si OO
O
O O OH
SiO
O
H
O OO
Si SiH
OMe
OMe
O Si OMe
OH
Si
NFC
OO
MeSi
H Si
O
OO
MeO
Reinforced silica aerogel
Multiscale assembly
Compatibilization
Polysiloxane layer,
NFC substrate
Utilization of silylated 3D nanocellulose scaffold to reinforce the mesoporous inorganic silica aerogel network
CNF
Bio-composite hydrogels,
super-absorbents,
sensors
Oil/water separation, removal of metal ions from water
Thermal insulation in
buildings
Barrier properties packaging, Functional films, 3-D printing, Coatings
CO2 capture for air
purification
Water repellency in coatings and
films
NH
2
mH
nC
Health and performance
Energy technologies,
Sust. Built Environment
Nanostructured materials Composite films
Natural Ressources and Pollutants
Acknowledgments
Dr. Philippe Tingaut and all present and former co-workers of the Cellulose Nanocomposites (new Functional Cellulose Materials) group Research and Industry partners CTI (Swiss National Agency for Research and Innovation) Gebert Rüf Foundation Swiss National Science Foundation (NFP66) European Commission under the 7th Framework Programme
Thank you for your attention!
contact: [email protected] [email protected]