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Nanocellulose – Materials, Functions and Environmental aspects
Orlando J. Rojas(1,2), Janne Laine(2) & Monika Österberg(2)
(1) North Carolina State University, USA (ojrojas@ncsu.edu)(2) Helsinki University of Technology, Finland
OECD Conference on Potential Environmental Benefits of Nanotechnology:Fostering Safe Innovation-Led Growth, Paris – France, 15-17 July 2009
Intro
2-D systems
3-D systems
Health & Safety
Environmental IssuesFinal Remarks
Intro
2-D systems
3-D systems
Health & Safety
Environmental IssuesFinal Remarks
Nanotechnology for the Forest Products Industry20062007 (Knoxville)2008 (St. Louis)2009 (Edmonton)2010 (Helsinki)
Lignocellulosic NanoStructures - Potential
CelluloseCellulose NanocrystalsNanofibrillar celluloseSpheresRegenerated nano-particlesElectrospun fibers
HemicellulosesSpheresFilmsElectrospun fibersSelf-associated structures
LigninSpheresRodsCylindersCarbon nanostructuresElectrospun fibersSelf-associated structures
◄
◄
◄
Top-down: deconstruction
Cellulose nanocrystals
L= 100-300 nm
W=10-20 znm
Top-down: Top-down: deconstruction
Cellulose: unique material Properties: biodegradability, chemical stability, multichirality, reactive hydroxyl groups and ability to form superstructures.
Cellulose nanocrystals
L= 100-300 nm
znm
Cellulose nanocrystals
L= 100-300 nm
W=10-20 znm
Intro
2-D systems
3-D systems
Health & Safety
Environmental IssuesFinal Remarks
Lignocellulosic NanoStructures Potential
Cellulose
Cellulose Nanocrystals
Nanofibrillar cellulose
Spheres
Regenerated nano-particles
Electrospun fibers
◄
Properties of Cellulose Nanocrystals
Optical Properties
Chirality
Magnetism
Self assembly
High surface
area
Strength
Cellulose Nanocrystals (CNXs)
Ramie SisalCotton
CrI Lmin Lmax lmin lmax Aspect
Ratio
88 50 200 10 20 16
CrI Lmin Lmax lmin lmax Aspect
Ratio
88 100 250 5 10 25
CrI Lmin Lmax lmin lmax Aspect
Ratio
81 70 200 3 6 14
Langmuir Isotherm (DODA surfactant)Su
rfac
e Pr
essu
re P
, mN
/m
A0, nm2/molecule
S
L2
I
L1
L1-G
G
L1-G
G
Sub-phase (water)
Movable barrier
Adsorbed surfactants
Langmuir-Schaeffer Technique
Cellulose Nanocrystals (CNX)
Cationic Surfactant (DODA)
DODA Surfactant + CNX
Langmuir-Schaeffer TechniqueLangmuir-Schaeffer (LS) Technique
Cellulose Nanocrystals (CNX)
Cationic Surfactant
Film transfer to solid support
Gold
SAM of a hydrophobic thiol
SAM of a Cellulose Nanocrystals
DODA
thiol Gold
Cellulose Nanocrystals
DODA DODA DODA
Alkali Stability and Alignment of CNX LS films
After alkaline treatment (0.01 M NaOH)
After alkaline treatment (0.1 M NaOH)
CNX Alignment
Enzyme Stability of CNX LS films
Before enzyme treatment After enzyme treatment
Case of Amorphous Films
Enzyme soln. injectionEnzyme soln. injection
Enzyme adsorptionSubstrate degradation
Enzyme adsorptionEnzyme adsorption
Quartz crystal
Enzyme soln. injectionEnzyme soln. injection
Quartz crystalQuartz crystalQuartz crystal
Cellulose film
Quartz crystal
Cellulose filmCellulose film
Substrate degradationSubstrate degradation
Quartz crystal
2m scan2m scan
Amorphous cellulose film
20 40 60
Time (min)0
20
40
60
80
100
120
-20
D(F
req
ue
ncy
), f
3/3
Case of CNX LS Films
Amorphous film hydrolysis
1. Alkali treatment to remove sulfate groups (25°C)2. Temperature adjustment (from 25°C to 40°C)3. Injection of buffer pH 54. Incubation with cellulase (Trichoderma reesei )
25 hours
Sisal
Cotton
Ramie
cellulases
Alkali treatment to remove sulfate groups (25°
20 40 60
Time (min)0
20
40
60
80
100
120
-20
D(F
req
uen
cy),
f 3/3
Time, min250 500 750 1000 1250 1500
-50
-40
0
-10
-20
-30(D
frequ
ency
), H
z
Before enzyme treatment After enzyme treatment
Enzymatic film hydrolysis : AFM
Intro
2-D systems
3-D systems
Health & Safety
Environmental IssuesFinal Remarks
Lignocellulosic NanoStructures
Cellulose
Cellulose Nanocrystals
Nanofibrillar cellulose
Spheres
Regenerated nano-particles
Electrospun fibers
◄
◄
Nanofibrillar Cellulose (homogenization & grinding)Nanofibrillar Cellulose (homogenization & grinding)
5×5 μm 1×1 μm
Lignocellulosic NanoStructures Potential
Cellulose
Cellulose Nanocrystals
Nanofibrillar cellulose
Spheres
Regenerated nano-particles
Electrospun fibers ◄
Electrospinning
-----Syringe
Pump
GroundedCollectorPositive
Tip+ + +
PowerSupply
Tip-Collector Distance
Voltage
ІІІІІІІ
Temperature Humidity
Air velocity
Ambient parameters
Viscosity Conductivity
Surface Tension
Electric FieldFlow Rate
TCD
Solution properties
ES Conditions
Fiber diameter
Reinforcement: CNXs
Polymer Matrices
Hydrophobic (PS, PCL):
Coupling agent (non-ionic surfactant)
Surface modification (chemical grafting)
Hydrophilic (PVA)
Reinforcement: CNXs (ramie fibers)
Polymer Matrices
Hydrophobic (PS, PCL):
Coupling agent (non-ionic surfactant)
Surface modification (chemical grafting)
Hydrophilic (PVA)
):
Coupling agent (non-ionic surfactant)
Surface modification (chemical grafting)
PS
+ CelluloseNanocrystals
+ Cellulose Nanocrystals+ Surfactant(Sorbitan monostearate)
http://www.elmarco.com
Polystyrene microfibers filled with cellulose nanocrystals
PS:CW:S=91:9:9
PS:CW:S=94:6:6
PS:CW:S=100:0:0
Storage tensile modulus E' versus temperature at 1 Hz for PS electrospun nanofibers filled with CNX
Reinforcement: CNXs (ramie fibers)
Polymer Matrices
Hydrophobic (PS, PCL):
Coupling agent (non-ionic surfactant)
Surface modification (chemical grafting)
Hydrophilic (PVA)
Coupling agent (non-ionic surfactant)
Surface modification (chemical grafting)
NCO
NCO
HO
O
O
OO
O
OHN
NH
n nO
HO
O
O
OO
OH
O
n n
+
O
O
CNX
TEAtoluene
TEAtoluene
OH
CNX
NCO
NHO
O
CNX
NCO
NHO
O
CNX +
Mn = 2,000 g/mol
Coupling agent
CNXs in Hydrophobic matrices: Grafting onto and grafting from (example – polycaprolactone)
Poly(caprolactones)-g-CNX
CNXs = 5%
220 + 55 nm
CNXs = 7.5%
310 + 45 nm
CNXs = 0%
210 + 40 nm
CNXs = 2.5%
120 + 30 nm
CNXs in polycaprolactone fibers
Reinforcement: CNXs (ramie fibers)
Polymer Matrices
Hydrophobic (PS, PCL):
Coupling agent (non-ionic surfactant)
Surface modification (chemical grafting)
Hydrophilic (PVA)
Surface modification (chemical grafting)
(PVA)
(1) Fully hydrolyzed(2) Partially hydrolyzed
(n = 0.88; m = 0.12)
Mw: 125 kDa
POLYMER MATRIX
Elastic polymerNon-toxicHydrophilic / water solubleBiocompatibleBiodegradable
CNXs in Hydrophilic matrices: PVACNXs in Hydrophilic matrices: PVA
POLYMER MATRIX
CNXs in Hydrophilic matrices: PVA
2 µm
CNX wt.%
fully
hyd
roly
zed
PVA
parti
ally
hyd
roly
zed
PVA
0
5
10
15
parti
ally
hyd
roly
zed
PVA
(100-250 nm)
Intro
2-D systems
3-D systems
Health & Safety
Environmental IssuesFinal Remarks
Nanotechnology: New products, new processes and a new approach to applying science.
Name is important: Supra/nano materialsNanomaterials in foodsNanomaterials in cosmeticsIn 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 StandardsEuropean 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
dose-response value and
correlation to human
experience.
Risk Management
Promote healthy workplace
through interventions,
recommendations and capacity
building
Collaboration
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)
Size
Shape
Composition
Solubility
Crystalline structure
Charge
Surface characteristics
Attached functional groups
Agglomeration
Impurities
Hazard:Parameters that could affect nanoparticletoxicity
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.
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
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/
1. All CNT are considered “new chemicals”
2. Each manufactured CNT is treated as unique3. Each has own PMN and ”consent” order
4. Uses and applications legally limited to those approved.5. All orders require 90-day inhalation TOX testing6. Full face respirator, impermeable gloves and clothing
Toxic Substances Control Act (TSCA):
Key initial question is “chemical identity”
(and whether the substance is new”)
(http://www.nanolawreport.com/articles/carbon-nanotubes/)
www.epa.gov/oppt/newchems/pubs/invntory.htm
Case of CNTs
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?
FPInnovation (see previous talk)
NCC as a material:Non toxicSimilar potency to NaCl and carboxymethyl cellulose (CMC)
Environmental concerns:Risks are lowAerosol exposure chamber - low risk determined
Case of nanocellulosic materials
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
Intro
2-D systems
3-D systems
Health & Safety
Environmental IssuesFinal Remarks
HOOH
H3
OOH
OCH3
OCH3
O
OCH3
H3CO
O
O
OC
O
OCH3
OCH3
OCH3
OH
O
HO
H3CO
HO
HO
H3CO
OCO
O
OH
OCH3
OCH3
OCH3
HOOH
H3
OOH
OCH3
OCH3
O
OCH3
H3CO
O
O
OC
O
OCH3
OCH3
C 3
OH
O
HO
H3CO
HO
O
HO
H3CO
HO
OO
OH
H3
OO
OH
H3
O H
HO
H3CO
OCO
O
OH
OCH3
OCH3
HO
H3CO
OCO
O
OH
OCH3
OCH3
OH
H3
OH
H3OCO
O
OCH3OCO
O
OCH3
OH
H3
OH
H3
O H
HO
H3CO
OCO
O
OH
OCH3
OCH3
HO
H3CO
OCO
O
OH
OCH3
OCH3
Lignin
Cellulose
& hemicelluloses
Energy
Sun, Air and water
Cryo-fracture deep-etch EMC. Haigler, NCSU
Cellulose
Nanofiber
bundles
6 Assembly proteins (rosette) which produces cellulose nanofibers
~28nm
Cryo-fracture deep-etch EM
6 Assembly proteins (rosette) which (rosette) which (rosette) which produces produces cellulose cellulose nanofibersnanofibers
Bottom-up: Nature working across 1010
scale(construction)
Cellulose
Nanofiber
bundlesbundles
(construction)
Top-down deconstruction
1x1 m
Nanofibrillar
2m scan2m scan
Spin coating
SAM
1x1 m
LB & LS
Cellulose Nanostructures
Gold Surface
S S SS S S SS S S SSS S SS
ElectrospinningNanocrystals
Nanocellulose Production
Intro
2-D systems
3-D systems
Health & Safety
Environmental Issues
Final Remarks
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 effects2.Size matters3.Regulatory approach should be case-specific4.Perception outside industry / government is critical
Figure from WikipediaFir0002/Flagstaffotos
NanotechIt is not discrete:
It is an interconnected web with many regulatory pointsThe failure in one regulatory point will affect technology developments of new and beneficial technological developments in several economic sectors
A challenge in nanotech
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?
Lignocellulosics – Most abundant renewable resource
Nanocellulosics – great opportunities
Applications, challenges, safety and environmental aspects
Conclusions
This project is supported by the National Research Initiative grant 2007-35504-18290 from the USDA Cooperative State Research, Education and Extension Service
Postdoctoral research associates:Youssef HabibiGerardo MonteroJooyoun Kim
Gradaute Students:Jusin ZoppeSoledad PeresinKelley SpenceXiaomeng Liu
Acknowledgements
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
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