Nanocellulose - Materials, functions and environmental aspects

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

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

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.


L= 100-300 nm

znm


L= 100-300 nm

W=10-20 znm

Intro

2-D systems

3-D systems

Health & Safety


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


Ratio

88 100 250 5 10 25


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


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


Lignocellulosic NanoStructures

Cellulose



Spheres


Electrospun fibers

◄

◄

Nanofibrillar Cellulose (homogenization & grinding)Nanofibrillar Cellulose (homogenization & grinding)

5×5 μm 1×1 μm

Lignocellulosic NanoStructures Potential

Cellulose



Spheres


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




Hydrophilic (PVA)

):



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


Polymer Matrices




Hydrophilic (PVA)



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


Polymer Matrices




Hydrophilic (PVA)


(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


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


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

Nanocellulose - Materials, functions and environmental aspects

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