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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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Hyperbranched Lignin Copolymers
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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Hyperbranched Lignin Copolymers
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.
M. D. Cannatelli, A. J. Ragauskas, Appl. Microbiol. Biotechnol. 2017, Submitted, In-Review.
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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Hyperbranched Lignin Copolymers
Proposed Reaction Mechanism
M. D. Cannatelli, A. J. Ragauskas, Appl. Microbiol. Biotechnol. 2017, Submitted, In-Review.
65% of material mass is
tris(2-mercaptoethyl)amine –
based on elemental analysis
Formation of a Copolymer Network
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Hyperbranched Lignin Copolymers
Thermal Analysis
M. D. Cannatelli, A. J. Ragauskas, Appl. Microbiol. Biotechnol. 2017, Submitted, In-Review.
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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Hyperbranched Lignin Copolymers
SEM Surface Characterization
M. D. Cannatelli, A. J. Ragauskas, Appl. Microbiol. Biotechnol. 2017, Submitted, In-Review.
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
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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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Hyperbranched Lignin Copolymers
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
M. D. Cannatelli, A. J. Ragauskas, Appl. Microbiol. Biotechnol. 2017, Submitted, In-Review.
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Hyperbranched Lignin Copolymers
13C NMR Data – DMSO-d6, 50°C
M. D. Cannatelli, A. J. Ragauskas, Appl. Microbiol. Biotechnol. 2017, Submitted, In-Review.
4° Ar-C4° Ar-C
Ar-C
C-H
Lignin
OCH3
CH3CH2
CH2
DMSO-d6
Ar-C
C-HLignin
OCH3 DMSOCH3
CH2CH2
Hyperbranched Lignin Copolymer
DEPT-135
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Hyperbranched Lignin Copolymers
1H-13C HMBC NMR Data – DMSO-d6, 50°C
M. D. Cannatelli, A. J. Ragauskas, Appl. Microbiol. Biotechnol. 2017, Submitted, In-Review.
J3 coupling between CH2 protons
of tris(2-mercaptoethyl)amine
and 4° Ar-C of
methylhydroquinone
Hyperbranched Lignin Copolymer
Evidence of covalent linkage between methylhydroquinone
and tris(2-mercaptoethyl)amine
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