A simple one-pot route to highly charged cationic ...costfp1205.com/wp-content/uploads/2017/events/Documents/Bangor … · A simple one-pot route to highly charged cationic cellulose

A simple one-pot route tohighly charged cationiccellulose nanocrystals

Latifah Jasmani, Samuel Eyley, RachelWallbridge, Wim Thielemans

Renewable Materials and Nanotechnology ResearchGroup, KU Leuven @ Kulak

Thursday 6th March 2014L. Jasmani, S. Eyley, R. Wallbridge, W. Thielemans, Nanoscale, 2013, 5,

10207–10211.

IntroductionCellulose nanocrystalsPrevious one-pot cationizations of CNCs

Our methodology

Results

Conclusion

Outline


Our methodology

Results

Conclusion

Sam Eyley Pyridinium grafted CNCs 3 / 20

Cellulose nanocrystals

I Derived from cottonI High cellulose contentI Bleached source commercially available

I Sulfuric acid (10.06 M) hydrolysis at 45 ◦CI Approximately 7nm×7nm cross section dimensionsI Purified by

I CentrifugationsI Dialysis with deionized waterI Mixed-bed ion exchange resin

I Freeze driedI What reactive groups are present on the surface of the

nanocrystals?

Introduction Methodology Results Conclusion


Nanocrystal surface

I Surface hydroxyl groups -∼ 3mmolg−1

I Primary 1 mmol g−1

I Secondary 2 mmol g−1

I Reactive 1−2mmolg−1

I Also consider:I Sulfate estersI Adsorbed waste species

from hydrolysisI Ethanol extraction removes

absorbed species andimproves consistency withesterificationsM. Labet and W. Thielemans, Cellulose, 2011, 18,

607–617.

NOH =n1 + n2

ρNAL1L2c

(L1 + L2d(110)

+L1 + L2d(11̄0)

)

NOH = Total number of surface hydroxyl groupsn1 = Number of 1◦ hydroxyls facing (110) in unit celln2 = Number of 2◦ hydroxyls facing (110) in unit cellc = Unit cell c dimensiond(110) = (110) plane spacingd(11̄0) = (11̄0) plane spacingρ = Density of crystalline celluloseNA = Avogadro’s constantL1 = Width of nanocrystalL2 = Height of nanocrystal

OHOH

O

OH

OO

OHOH

OH OHOH

O

OH

O

OH

O

OH

OMe

OMe OH

OMe

OMe

xylobiose 1,6-anhydroglucose

vanillic acid 3,4,5-trimethoxyphenol



Nanocrystal surface

I Surface hydroxyl groups -∼ 3mmolg−1

I Primary 1 mmol g−1

I Secondary 2 mmol g−1

I Reactive 1−2mmolg−1

I Also consider:I Sulfate estersI Adsorbed waste species

from hydrolysisI Ethanol extraction removes

absorbed species andimproves consistency withesterificationsM. Labet and W. Thielemans, Cellulose, 2011, 18,

607–617.

NOH =n1 + n2

ρNAL1L2c

(L1 + L2d(110)

+L1 + L2d(11̄0)

)

NOH = Total number of surface hydroxyl groupsn1 = Number of 1◦ hydroxyls facing (110) in unit celln2 = Number of 2◦ hydroxyls facing (110) in unit cellc = Unit cell c dimensiond(110) = (110) plane spacingd(11̄0) = (11̄0) plane spacingρ = Density of crystalline celluloseNA = Avogadro’s constantL1 = Width of nanocrystalL2 = Height of nanocrystal

OHOH

O

OH

OO

OHOH

OH OHOH

O

OH

O

OH

O

OH

OMe

OMe OH

OMe

OMe

xylobiose 1,6-anhydroglucose

vanillic acid 3,4,5-trimethoxyphenol



Previous one-pot cationizations of CNCs

I Glycidyltrimethylammonium chlorideI First reported by Hasani et al. - DS 0.02 - Surface DS 0.1

M. Hasani, E. D. Cranston, G. Westman and D. Gray, Soft Matter, 2008, 4, 2238–2244.

CelO

OH

N+Cl –

a) 7% NaOH(aq) , 30 min

OHOH

O

OH

OH

O OOH

OH

OH

OH

n

Cel-OH = b) 1 eq. GTMAC, 65°C, 5 h

I Thixotropic suspensionsI BirefringenceI Low degree of substitutionI Hydrolysis of GTMAC by aqueous NaOHI 15 day purification




I Glycidyltrimethylammonium chlorideI First reported by Hasani et al. - DS 0.02 - Surface DS 0.1

M. Hasani, E. D. Cranston, G. Westman and D. Gray, Soft Matter, 2008, 4, 2238–2244.

CelO

OH

N+Cl –

a) 7% NaOH(aq) , 30 min

OHOH

O

OH

OH

O OOH

OH

OH

OH

n

Cel-OH = b) 1 eq. GTMAC, 65°C, 5 h

I Thixotropic suspensionsI BirefringenceI Low degree of substitutionI Hydrolysis of GTMAC by aqueous NaOHI 15 day purification




I Glycidyltrimethylammonium chlorideI Zaman et al. suggest use of “semi-dry” method

M. Zaman, H. Xiao, F. Chibante and Y. Ni, Carbohydr. Polym., 2012, 89, 163–170.

I Limit hydrolysis of GTMACCel

O

OH

N+Cl –

a) NaOH(s) , 5 min

OHOH

O

OH

OH

O OOH

OH

OH

OH

n

Cel-OH = b) DMSO/H2O 3 eq. GTMAC, 65°C, 4 h

I DS 0.35 - Surface DS 0.78 for 5nm widthI No crystallinity informationI 3:1 GTMAC:AGU (DS 0.35)




I Glycidyltrimethylammonium chlorideI Zaman et al. suggest use of “semi-dry” method

M. Zaman, H. Xiao, F. Chibante and Y. Ni, Carbohydr. Polym., 2012, 89, 163–170.

I Limit hydrolysis of GTMACCel

O

OH

N+Cl –

a) NaOH(s) , 5 min

OHOH

O

OH

OH

O OOH

OH

OH

OH

n

Cel-OH = b) DMSO/H2O 3 eq. GTMAC, 65°C, 4 h

I DS 0.35 - Surface DS 0.78 for 5nm widthI No crystallinity informationI 3:1 GTMAC:AGU (DS 0.35)


Outline


Our methodology

Results

Conclusion


Our methodology - esterification

I In-situ acid anhydride formation using tosyl chlorideI Reported for acetylation of cellulose fibres by Shimizu and

Hayashi in 1988Y. Shimizu and J. Hayashi, Sen’i Gakkaishi, 1988, 44, 451–456

I 6:6:1 TsCl:AcOH:AGU leads to DS 2−3I Our system: 0.9:0.9:1 TsCl:Acid:AGU

I Two acids containing alkyl bromides

Br

O OH

Br

O OH



Our methodology - esterification

I In-situ acid anhydride formation using tosyl chlorideI Reported for acetylation of cellulose fibres by Shimizu and

Hayashi in 1988Y. Shimizu and J. Hayashi, Sen’i Gakkaishi, 1988, 44, 451–456

I 6:6:1 TsCl:AcOH:AGU leads to DS 2−3I Our system: 0.9:0.9:1 TsCl:Acid:AGU

I Two acids containing alkyl bromides

Br

O OH

Br

O OH



Our methodologyI Simultaneous esterification and nucleophilic substitutionI Suspend 0.9:0.9:1 TsCl:Acid:AGU in pyridine

I 80 ◦C for 16 hI Argon atmosphere

SO

O Cl

R Br

OOH

N

N

R N+

O O –

N+

R

O OTs

Br /Cl–

OH Cel

R N+

O–

O+

OTs

H

Cel

Br /Cl–

N

N+

R

O O

Cel

Br /Cl/TsO–

R=H, Me

[PyH]Br

[PyH][Br /Cl]

[PyH][Br /Cl]2[PyH][Br/Cl/TsO]



Our methodology - purification

I Soxhlet extractionI Dichloromethane -

24 hI Ethanol - 72 hI Dried under vacuum


Outline


Our methodology

Results

Conclusion


FTIR - confirmation of esterification

4000 3500 3000 2500 2000 1500 1000 500

Wavenumbers /cm-1

v(C=O) v(C=C)

CNCs [Br/Cl/TsO][BnPy]-g-CNCs [Br/Cl/TsO][MeBnPy]-g-CNCs

v(C-Br)?ω(C-H arom.)?



XPS - confirmation of esterification

2000

1500

1000

500

CP

S

296 292 288 284Binding Energy /eV

1800

1600

1400

1200

1000

800

600

400

200

296 292 288 284

Raw data C-C/C=C C-O O-C-O O-C=O Shake-up Background Calculated profile

[Br][BnPy]-g-CNCs [Br][MeBnPy]-g-CNCs



XPS - confirmation of nucleophilic substitution

I One N 1senvironment

I Binding energyconsistent withpositivelychargednitrogen

500

450

400

350

300

CP

S


450

400

350

300

406 404 402 400

402.08 eV402.01 eV




XPS - confirmation of nucleophilic substitution

I One Br 3denvironment

I Binding energyfor 5/2 bandconsistent withbromide

200

150

100

50

CP

S


120

100

80

60

40

72 70 68 66

67.38 eV 67.39 eV

5/2 3/2




Elemental Analysis - DS

I DS calculated from elemental analysisI Halogen analysis not specificI Surface DS based on crystallite size from XRD

Product C /% H /% N /% Hal. /% DS DSsurf

[Br][BnPy]-g-CNCs - Found 45.4 5.69 0.71 4.80 – –C7.24H10.96O5.10N0.1Br0.1 - Calc. 46.1 5.86 0.71 4.05 0.10 0.31[Br][MeBnPy]-g-CNCs - Found 48.3 5.46 1.59 8.60 – –C9.84H13.29O5.27N0.27Br0.27 - Calc. 48.9 5.46 1.59 9.07 0.27 0.85

I Difference in DS - solubility of pyridinium intermediateI High substitution - crystallinity affected?



Structural integrity - XRD

I Crystallinity determined bypattern fitting

I Subtract instrumentalbackground

I Background =Amorphous content

Product % Cryst. % Mod. Total

CNCs 88 0 88[Br][BnPy]-g-CNCs 69 16 85[Br][MeBnPy]-g-CNCs 58 32 90

I Amorphous graftsI No loss of cellulose

crystallinity

Offs

et N

orm

aliz

ed In

tens

ity

403530252015102θ

Raw data Purified [Br][BnPy]-g-CNCs [Br][MeBnPy]-g-CNCs



Surface charge

I Surface charge determined by Orange IIdye adsorption

I Mixed with excess Orange II solutionfor 1 minute

I CNCs removed by filtrationI Difference in concentration measured

by UV-Vis

Product Amount of Dye Surface +ve Charge Density

CNCs 0 mmol g−1 –[Br][BnPy]-g-CNCs 0.49 mmol g−1 1.08 e nm−2

[Br][MeBnPy]-g-CNCs 0.82 mmol g−1 1.81 e nm−2

O

S

O O

N

N

HO



High surface charge density

I Products form stablesuspension in water aftercomplete drying in vacuo

I 7 % dispersion showsbirefringence when viewedthrough crossed polarizers


Outline


Our methodology

Results

Conclusion


Conclusion

I Successfully cationized CNCs using esterificationI DS 0.27 almost as high as Zaman et al. (DS 0.35)

I Over 3 times lower reagent excessI Crystallinity still intact

I Lower grafting for [Br][BnPy]-g-CNCs due to solubility ofintermediate

I Highly charged products able to be re-dispersed in waterfully after complete drying in vacuo



Future Work

I Absolute identification of anionic composition of productI Study binding affinities for different anionsI Test hydrolytic stability of productsI Optimize reaction conditions - reduce excessI Optimize reaction conditions - cost [Br][MeBn]-g-CNCs



Acknowledgements

I Latifah JasmaniI Rachel WallbridgeI Wim ThielemansI Emily Smith - XPSI Ian Blakeley - EA
