laccase-facilitated copolymerization of lignin for the...

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Laccase-Facilitated Copolymerization of Lignin for the Synthesis of Novel

Biomaterials

Mark D. Cannatelli

Dr. Arthur J. Ragauskas

Renewable Bioproducts Institute

Department of Chemistry

Georgia Tech

2D. Kai, Z. W. Low , S. S. Liow , A. A. Karim, H. Ye, G. Jin, K. Li, X. J. Loh, ACS Sustainable Chem. Eng. 2016, 3(9), 2160-2169.

Hyperbranched Lignin Copolymers

Kraft Lignin Functionalized with PEGMA

Combining with α-cyclodextrin

produces hydrogels• Mechanically responsive• Self-healing properties

• No cytotoxicity

Y. Zheng, S. Li, Z. Weng, C. Gao, Chem. Soc. Rev. 2015, 44, 4091-4130.

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• Fungi – lignin degradation

• Plants – lignin biosynthesis

U. N. Dw ivedi, P. Singh, V. P. Pandey, A. Kumar, J. Mol. Catal. B: Enzym. 2011, 68, 117-128.

B. Otto, D. Schlosser, W. Reisser, Arch. Microbiol. 2010, 192, 759-768.

M. D. Cannatelli, A. J. Ragauskas, Chem. Rec. 2017, 17(1), 122-140.

Laccases

• Benzenediol : oxygen

oxidoreductases

• EC: 1.10.3.2

• Multi-copper oxidases

PDB: 1GYC

E. I. Solomon, A. J. Augustine, J. Yoon, Dalton Trans. 2008, 30, 3921-3932.

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Laccase & Lignin

Radical-Radical Coupling Reactions

Nucleophilic Attack on Quinone Methide Intermediate

M. D. Cannatelli, A. J. Ragauskas, Appl. Microbiol. Biotechnol. 2016, 100(20), 8685-8691.

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Laccase-Catalyzed Coupling Chemistry

M. D. Cannatelli, A. J. Ragauskas, J. Mol. Catal. B: Enzym. 2015, 119, 85-89.

Laccase-Catalyzed Coupling of 1,2-Ethanedithiol with Hydroquinones

- Lignin Model Compound Studies

3,4-(Ethylenedithio)avaroneAnti-cancer agent

Established thiols as good

candidates for nucleophilic addition to para-quinones

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Value of a lignin core• Renewable• Biodegradable

• Nontoxic• Abundant• Inexpensive

M. D. Cannatelli, A. J. Ragauskas, Appl. Microbiol. Biotechnol. 2017, Submitted, In-Review.

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Lignin Source, Purification, and Structural Characterization

Softwood kraft lignin

Purification

1) EDTA treatment

2) Soxhlet extraction

3) Dioxane/Water extraction

GPC Data

Mw = 2,350 g/mol

PDI: 2.37

Characterization of hydroxyl group content

via 31P NMR- After derivatization with TMDP

Y. Pu, S. Cao, A. J. Ragauskas, Energy Environ. Sci. 2011, 4, 3154-3166.


Structure mmol/

g lignin

COOH 0.3095

p-Hydroxy phenyl OH 0.1249

Guaiacyl OH 2.0580

C5 Condensed OH 1.8353

Aliphatic OH 1.9928

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Proposed Reaction Mechanism


65% of material mass is

tris(2-mercaptoethyl)amine –

based on elemental analysis

Formation of a Copolymer Network

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Thermal Analysis


TGA DSC – Hyperbranched Lignin Copolymer

Td (°C)

Tp (°C)

Tg (°C)

% Mass at 500°C

Purified kraft lignin 152 166 - 52

Hyperbranched lignin copolymer 238 266 50-60 22

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SEM Surface Characterization


Hyperbranched Lignin Copolymer – Top View

Hyperbranched Lignin Copolymer – Cross SectionPurified Kraft Lignin

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Conclusions & Future Work

• Laccases are biotechnological tools with great potential to advance sustainability within the

chemical industry

• Fundamental laccase-catalyzed coupling chemistry can be applied to the functionalization of

lignin for the synthesis of LCHCs → novel route for lignin valorization

• Material likely exists as a copolymeric network

• Preliminary results show LCHC material exhibits good thermostability

• Future studies:

- collaborate with materials scientists to develop a novel lignin based biomaterial

that’s tailored for a particular application (e.g. thermoplastic, resin adhesive)

- different monomer selection

- addition of a plasticizer into the formulation

- may assess adhesive properties

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Acknowledgments

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwiPhfK6-snOAhVGTCYKHTp5AOIQjRwIBw&url=http://www.tappinano.org/conferences/poster-winners/&psig=AFQjCNHQ2TbB8WiKVUWXEN0S6MoPxe2wig&ust=1471575041295470

http://www.google.com/url?sa=i&rct=j&q=&esrc=s&source=images&cd=&cad=rja&uact=8&ved=0ahUKEwiPhfK6-snOAhVGTCYKHTp5AOIQjRwIBw&url=http://www.tappinano.org/conferences/poster-winners/&psig=AFQjCNHQ2TbB8WiKVUWXEN0S6MoPxe2wig&ust=1471575041295470

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Circular Economy & Biorefinery

W. R. Stahel, Nature 2016, 531, 435-438.

Circular Economy

Biorefining in the Forest Products Industry

A. J. Ragauskas, G. T. Beckham, M. J. Biddy, R. Chandra, F. Chen et al., Science 2014, 344, 1246843-1.

Constituents of Woody Biomass

A. J. Ragauskas, C. K. Williams, B. H. Davison, G. Britovsek, J. Cairney et al., Science 2006, 311, 484-489.

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Lignin

A. J. Ragauskas, G. T. Beckham, M. J. Biddy et al., Science 2014, 344, 1246843-1.

Monolignols

• Irregular, amorphous polymer of oxidatively coupled 4-hydroxyphenylpropanoid

units

• Second most abundant terrestrial biopolymer on Earth

• In woody biomass, provides mechanical support, water conductive, and

antimicrobial properties

• 50 M tpy produced by global pulp and paper industry (Kai et al., 2016)

• 2% used for valuable products - dispersants and binders (Lora and Glasser, 2002)

• Forecasted: 62 M tpy to be produced within the next decade in the US from industrial cellulosic ethanol production (Langholtz et al., 2014)

Isolated Kraft Lignin

D. Kai, Z. W. Low , S. S. Liow et al., ACS Sustainable Chem. Eng. 2016, 3, 2160-2169.

J. H. Lora, W. G. Glasser, J. Polym. Environ. 2002, 10, 39-48.

M. Langholtz, M. Dow ning, R. Graham et al., SAE Int. J. Mater. Manf. 2014, 7, 115-121. M. D. Cannatelli, A. J. Ragauskas, Appl. Microbiol. Biotechnol. 2016 , 100(20), 8685-8691.

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Laccase & Lignocellulosics

R. P. Chandra, A. J. Ragauskas, Enzyme Microb. Technol. 2002, 30(7), 855-861.

M. D. Cannatelli, A. J. Ragauskas, Chem. Rec. 2017, 17(1), 122-140.

Laccase-Mediated Functionalization of Lignocellulosic Fibers with Phenols

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Broadening of peaks indicative of polymerization

1H NMR Data – DMSO-d6, 50°C

Hyperbranched Lignin Copolymer

Pure Kraft

Lignin

Phenolic OH

Ar-H

CH3

CH2

CH2

SH

OCH3

Ar-H

Phenolic OH

CH3

CH2

Ar-H

Phenolic OH OCH3


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13C NMR Data – DMSO-d6, 50°C


4° Ar-C4° Ar-C

Ar-C

C-H

Lignin

OCH3

CH3CH2

CH2

DMSO-d6

Ar-C

C-HLignin

OCH3 DMSOCH3

CH2CH2


DEPT-135

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1H-13C HMBC NMR Data – DMSO-d6, 50°C


J3 coupling between CH2 protons

of tris(2-mercaptoethyl)amine

and 4° Ar-C of

methylhydroquinone


Evidence of covalent linkage between methylhydroquinone

and tris(2-mercaptoethyl)amine

laccase-facilitated copolymerization of lignin for the...

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