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Volume 3, Issue 2 (Suppl) Trends in Green chem
ISSN: 2471-9889 Environmental & Green Chemistry 2017
July 24-26, 2017
Page 39
5 th International Conference on
&
6 th International Conference on
July 24-26, 2017 Rome, Italy
Green Chemistry and Technology
Environmental Chemistry and Engineering
Towards carbon fibers from single component kraft lignin systems: An application of green chemistry
with forest biomaterials
C arbon fibers represent a class of materials with enormous potential for many materials and other engineering applications
for our society. There are projections that by 2020 the actual demand for carbon fibers will be such that the traditional poly-
acrylonitrile precursors used today will not be enough to address the projected demand. Consequently, it is imperative that
new precursors based on the foundations of green chemistry need be developed. In this respect, technical lignins present us
with formidable challenges but also with enormous opportunities and they are to be explored in detail during this presentation.
In our earlier effort, we have embarked in describing and discussing the importance of propargylation chemistry on lignin so
as to synthesize lignin macromonomers for thermal polymerization via Claisen rearrangement. We have also discussed that
the molecular weight and glass transition temperatures of the thermally polymerized lignin improves significantly relative to
the starting material. The intricate polymer structure created within lignin as a result of the benzopyran double bond thermal
polymerization chemistry is offering a regular covalently linked framework from which, after carbonization, a regular carbon
fiber material could. As such, thermally polymerized propargylated softwood lignin emerges as a prospective material for the
synthesis of bio-based carbon fiber precursor. Various reactivity considerations that are to be discussed in the presentation
were addressed by a series of experiments where initially Acetone Soluble Kraft Lignin (ASKL) was propargylated, thus
occupying all readily accessible and highly reactive phenolic–OHs, followed by methylation of the remaining phenolic OH’s
to limit phenoxy radical induced thermal polymerization. All the polymerization reactions were conducted by heating the
samples at 180°C for three hours and the corresponding molecular weights and distributions were determined. As anticipated,
the installation of the propargyl groups in more reactive positions, more readily prone to Claisen rearrangement and thermal
polymerization events, offered much better developed molecular weights able to offer carbon fibers.
Scheme 1: The sequence of reactions that involves lignin propargylation (A) followed by Claisen rearrangement (B) and
thermal polymerization (C)
Biography
Dimitris SArgyropoulos, Professor of Chemistry at North Carolina State University, is internationally recognized for his leading contributions to Green Chemistry using wood
biopolymers. His work focuses on promoting our understanding of the structure and reactivity of lignin and the development of novel NMR and material science techniques
for the structural elucidation and the upgrading of these biopolymers representing otherwise unsolved, intractable problems in lignin based material’s chemistry. The efforts
of his research group have been disseminated in excess of 200 scientific papers, numerous scientific conferences and invited presentations.
Dimitris S Argyropoulos
North Carolina State University, USA
Dimitris S Argyropoulos, Trends in Green chem, 3:2
DOI: 10.21767/2471-9889-C1-001
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