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: tanja.zimmermann@empa.ch thomas.geiger@empa.ch