OECD Conference on Potential Environmental Benefits of Nanotechnology:
Fostering Safe Innovation-Led Growth, Paris – France, 15-17 July 2009
Nanocellulose – Materials, Functions
and Environmental aspects
Orlando J. Rojas(1,2), Janne Laine(2) & Monika Österberg(2)
(1) North
Carolina State University, USA ([email protected])
(2) Helsinki University of Technology, Finland
2-D systems
Intro
3-D systems
Health &
Safety
Final Remarks
Environmental
Issues
2-D systems
Intro
3-D systems
Health &
Safety
Final Remarks
Environmental
Issues
Nanotechnology for the Forest
Products Industry
2006
2007 (Knoxville)
2008 (St. Louis)
2009 (Edmonton)
2010 (Helsinki)
Lignocellulosic NanoStructures - Potential
Cellulose
Lignin
Cellulose Nanocrystals ◄
Spheres
Nanofibrillar cellulose ◄
Rods
Spheres
Regenerated nano-particles
Electrospun fibers ◄
Hemicelluloses
Spheres
Films
Electrospun fibers
Self-associated structures
Cylinders
Carbon nanostructures
Electrospun fibers
Self-associated structures
Cellulose nanocrystals
L= 100-300 nm
W=10-20 znm
Top-down:
deconstruction
Cellulose: unique material
Properties: biodegradability, chemical
stability, multichirality, reactive hydroxyl
groups and ability to form superstructures.
2-D
systems
Intro
3-D systems
Health &
Safety
Final Remarks
Environmental
Issues
Lignocellulosic NanoStructures Potential
Cellulose
Cellulose Nanocrystals
Nanofibrillar cellulose
Spheres
Regenerated nano-particles
Electrospun fibers
◄
Properties of Cellulose Nanocrystals
Optical
Properties
Strength
Chirality
High
surface
area
Magnetism
Self
assembly
CrI
Lmin
Ramie
Cellulose Nanocrystals (CNXs)
Cotton
Lmax
Aspect
lmin
lmax
CrI
Lmin
Lmax
lmin
lmax
Ratio
88
100
250
5
10
25
Aspect
CrI
Lmin
Sisal
Lmax
lmin
lmax
Ratio
88
50
200
10
20
16
Aspect
Ratio
81
70
200
3
6
14
Surface Pressure P, mN/m
Langmuir Isotherm (DODA surfactant)
S
L2
I
L1
L1-G
G
A0, nm2/molecule
Adsorbed surfactants
Sub-phase (water)
Movable barrier
DODA SurfactantTechnique
+ CNX
Langmuir-Schaeffer
Cationic Surfactant (DODA)
Cellulose
Nanocrystals (CNX)
Langmuir-Schaeffer
(LS)
Technique
Langmuir-Schaeffer
Technique
Cationic Surfactant
Cellulose
Nanocrystals (CNX)
Film transfer to solid support
Gold
SAM of a
hydrophobic
thiol
thiol
Gold
DODA
Cellulose
Nanocrystals
DODA
Cellulose Nanocrystals
Alkali Stability and Alignment of CNX LS films
After alkaline treatment
(0.01 M NaOH)
CNX Alignment
After alkaline treatment
(0.1 M NaOH)
Enzyme Stability of CNX LS films
Before enzyme treatment
After enzyme treatment
Case of Amorphous Films
2m scan
Amorphous cellulose film
-20
Cellulose film
Quartz crystal
20
0
40
60
Time (min)
20
40
60
Cellulose film
80
Quartz crystal
Enzyme adsorption
100
120
D(Frequency), f3/3
Enzyme soln. injection
Cellulose film
Quartz crystal
Substrate degradation
Case of CNX LS Films
Alkali treatment to remove sulfate groups (25°
(25°C)
Temperature adjustment (from 25°C to 40°C)
Injection of buffer pH 5
Incubation with cellulase (Trichoderma reesei )
1.
2.
3.
4.
Time, min
250
40
Time (min)
100
D(Frequency), f3/3
20
80
1000
1250
1500
Cotton
60
(Dfrequency), Hz
20
0
60
750
-50
-20
40
500
-40
Ramie
-30
Sisal
-20
cellulases
-10
0
120
Amorphous film hydrolysis
25 hours
Enzymatic film hydrolysis : AFM
Before enzyme treatment
After enzyme treatment
2-D systems
Intro
3-D systems
Health &
Safety
Final Remarks
Environmental
Issues
Lignocellulosic NanoStructures
Cellulose
Cellulose Nanocrystals
Nanofibrillar cellulose
◄
Spheres
Regenerated nano-particles
Electrospun fibers
◄
Nanofibrillar Cellulose (homogenization & grinding)
5×5 μm
1×1 μm
Lignocellulosic NanoStructures Potential
Cellulose
Cellulose Nanocrystals
Nanofibrillar cellulose
Spheres
Regenerated nano-particles
Electrospun fibers
◄
Fiber diameter
Electrospinning
ES Conditions
Voltage
Positive
Tip
ІІІІІІІ + + +
Syringe
Pump
TipCollector
Distance
-
Grounded
Collector
Electric Field
Flow Rate
TCD
Solution properties
Viscosity
Conductivity
Surface Tension
Ambient parameters
Power
Supply
Temperature
Humidity
Air velocity
Polymer Matrices
Reinforcement: CNXs
Hydrophobic (PS, PCL):
Coupling agent (non-ionic surfactant)
Surface modification (chemical grafting)
Hydrophilic (PVA)
Polymer Matrices
Reinforcement: CNXs
(ramie fibers)
Hydrophobic (PS, PCL):
):
Coupling agent (non-ionic surfactant)
Surface modification (chemical grafting)
Hydrophilic (PVA)
PS
+ Cellulose
Nanocrystals
+ Cellulose Nanocrystals
+ Surfactant
(Sorbitan monostearate)
http://www.elmarco.com
Polystyrene microfibers filled with cellulose nanocrystals
Storage tensile modulus E' versus temperature at 1 Hz for
PS electrospun nanofibers filled with CNX
PS:CW:S=91:9:9
PS:CW:S=94:6:6
PS:CW:S=100:0:0
Polymer Matrices
Reinforcement: CNXs
(ramie fibers)
Hydrophobic (PS, PCL):
Coupling agent (non-ionic surfactant)
Surface modification (chemical grafting)
Hydrophilic (PVA)
CNXs in Hydrophobic matrices: Grafting onto and grafting
from (example – polycaprolactone)
NCO
Coupling agent
NCO
OH
+
CNX
NCO
O
CNX
TEA
toluene
NH
O
NCO
O
CNX
O
NH
O
O
+
O
H
O
nO
O
O
nH
TEA
toluene
Mn = 2,000 g/mol
O
H
N
O
O
O
nO
O
O
O
CNX
O
NH
O
Poly(caprolactones)-g-CNX
nH
CNXs in polycaprolactone fibers
CNXs = 0%
CNXs = 2.5%
210 + 40 nm
120 + 30 nm
CNXs = 5%
CNXs = 7.5%
220 + 55 nm
310 + 45 nm
Polymer Matrices
Reinforcement: CNXs
(ramie fibers)
Hydrophobic (PS, PCL):
Coupling agent (non-ionic surfactant)
Surface modification (chemical grafting)
Hydrophilic (PVA)
CNXs in Hydrophilic matrices: PVA
POLYMER MATRIX
(1) Fully hydrolyzed
(2) Partially hydrolyzed
(n = 0.88; m = 0.12)
Mw: 125 kDa
Elastic polymer
Non-toxic
Hydrophilic / water soluble
Biocompatible
Biodegradable
fully hydrolyzed PVA
5
10
15
partially hydrolyzed PVA
CNX wt.%
0
2 µm
(100-250 nm)
2-D systems
Intro
3-D systems
Health &
Safety
Final Remarks
Environmental
Issues
Nanotechnology: New products, new processes and
a new approach to applying science.
Name is important:
Supra/nano materials
Nanomaterials in foods
Nanomaterials in cosmetics
In forest?
(cellulose nanocrystals, nanocrystalline cellulose, cellulose whiskers)
Note: There are no standard reference nanomaterials
TC229: Definition about Forest or Lignocellulose
Nanotechnology?
ISO/TC 229 International Standards
European standards: CEN / TC 352
Early development of standards for the broad, major
technology domain of nanotechnologies
Nomenclature model challenges for building the
appropriate regulatory environment
Requirements for measurement and metrology for
nanotechnology
A good thing:
Developing standards before commercial deployment
Risks
Risk = f (hazard , exposure)
Hazard: Biological activity – toxicity.
What is known and is there anything new?
Exposure: Where, to what, to what extent, can it
be measured?
Unknown and uncertainties
+
Rapidly evolving technology
=
Risk management approach
NIOSH &
Nanotechnology
Hazard
Assessment
Determine
whether
nanoparticles
&
nanomaterials
pose risk of
injuries and
illness to
workers
Risk
Assessment
Conduct
research to
develop a
doseresponse
value and
correlation
to human
experience.
Risk Management
Collaboration
Promote healthy
workplace
through
interventions,
recommendations
and capacity
building
Enhance global
workplace safety
and health
through national
and international
collaboration on
nanotechnology.
Center for Disease Control and Prevention, NIOSH (the info disseminated here have not been
formally disseminated by NIOSH and cannot be taken to represent their determination or policy)
Hazard:
Parameters
that could
affect
nanoparticle
toxicity
Size
Shape
Composition
Solubility
Crystalline structure
Charge
Surface characteristics
Attached functional groups
Agglomeration
Impurities
While nano materials are already appearing in
commerce there has been only limited research on
their potential toxicity.
The same unusual chemical and physical properties
that make nanomaterials useful also make their
interactions with biological systems difficult to
anticipate and study.
The unique and diverse physicochemical properties
of nanoscale materials suggest that toxicological
properties may differ from materials of similar
composition but different size.
Are nanomaterials safe?
=
Are chemicals safe?
There is no single nanomaterial!
Nanoparticles: Many shapes, many chemistries
Not all nanoparticles are the same
http://www.sciencedaily.com/
Case of CNTs
1. All CNT are considered “new chemicals”
2. Each manufactured CNT is treated as unique
3. Each has own PMN and ”consent” order
4. Uses and applications legally limited to those approved.
5. All orders require 90-day inhalation TOX testing
6. Full face respirator, impermeable gloves and clothing
(http://www.nanolawreport.com/articles/carbon-nanotubes/)
Toxic Substances Control Act (TSCA):
www.epa.gov/oppt/newchems/pubs/invntory.htm
Key initial question is “chemical identity”
(and whether the substance is new”)
Hazard and Risk Picture:
Carbon Nanotubes
Aspiration of SWCNT:
•Rapid but transient inflammations and
damage
•Granulomas and fibrosis at deposition
sites of large agglomerates of
SWCNT
Note conflicting reports – there is need
for more research
Image from
http://jnm.snmjournals.org
Cellulose Nanocrystals?
Case of nanocellulosic materials
FPInnovation (see previous talk)
NCC as a material:
Non toxic
Similar potency to NaCl and carboxymethyl cellulose (CMC)
Environmental concerns:
Risks are low
Aerosol exposure chamber - low risk determined
Cellulose: 100+ different cellulose “substances” in EPA’s Substance
Registry Services (http://iaspub.epa.gov/sor_internet/registry/substreg)
NCC production:
H2SO4 at 45, 65 and 86% concentrations
Yields of 22, 30 and 20%, respectively
2-D systems
Intro
3-D systems
Health &
Safety
Final Remarks
Environment
al Issues
Sun, Air and water
Cellulose
& hemicelluloses
H3CO
HO
H3CO
O
OCH3
O
O
O
OCH3
OCH3OCH3
OCH3
OH
O
HO
OH
O
O
HO
OH
OCH3
Lignin
HO
OH
H3CO
OCH3
OCH3OCH3
OCH
O
CH3
OH
O
O
Energy
OH
O
OCH3
O
HO
OH
H3CO
OCH3
OCH3OCH3
O
O
OCH3OCH3
OH
O
OH
6 Assembly
proteins
(rosette) which
produces
cellulose
nanofibers
Cellulose
Nanofiber
bundles
~28nm
Cryo-fracture deep-etch EM
C. Haigler, NCSU
Top-down
Bottom-up:
deconstruction
Nature working
across 1010
scale
(construction)
Cellulose Nanostructures
1x1 m
1x1 m
SSSSSSSSSSSSS
Gold Surface
Nanofibrillar
SAM
LB & LS
Nanocrystals
Electrospinning
2m scan
Spin coating
Nanocellulose Production
2-D systems
Intro
3-D systems
Health &
Safety
Final
Remarks
Environmental
Issues
Council Academy of Canada:
There are inadequate data to asses risk assessment
Workshop on Risk Assessment Issues for
Manufactured Nanomaterials (Sept, 2009, DC)
Repeated themes:
1.Uncertainty in understanding nano-specifics
attributes and environmental effects
2.Size matters
3.Regulatory approach should be case-specific
4.Perception outside industry / government is critical
A challenge in nanotech
Nanotech
It is not discrete:
It is an interconnected web with many regulatory
points
The failure in one regulatory point will affect
technology developments of new and beneficial
technological developments in several economic
sectors
Figure from Wikipedia
Fir0002/Flagstaffotos
Nanotechnology
Public reaction can lead to irrational rejection
of nanotechnology
Need balance for discourse on risk and
benefits to ensure progress accords to
societal values
How this can be incorporated into regulatory
decision making is still unclear!
What about nanocellulose?
Conclusions
Lignocellulosics – Most abundant
renewable resource
Nanocellulosics – great
opportunities
Applications, challenges, safety
and environmental aspects
Acknowledgements
Postdoctoral research associates:
Youssef Habibi
Gerardo Montero
Jooyoun Kim
Gradaute Students:
Jusin Zoppe
Soledad Peresin
Kelley Spence
Xiaomeng Liu
This project is supported by the
National Research Initiative grant
2007-35504-18290 from the USDA
Cooperative State Research,
Education and Extension Service
Many concerns are not specific to nanomaterials or
nanotechnologies
Engage risk analysis with product engineers
Long term data is needed
Need to conduct expert workshops to identify issues