Volume 3 • Issue 3 • 1000e123 J Biotechnol Biomater ISSN: 2155-952X JBTBM, an open access journal Editorial Open Access Biotechnology & Biomaterials Argyropoulos, J Biotechnol Biomater 2013, 3:3 http://dx.doi.org/10.4172/2155-952X.1000e123 *Corresponding author: Dimitris S Argyropoulos, Department of Chemistry and Forest Biomaterials, North Carolina State University, Raleigh, NC, USA, E-mail: dsargyro@ncsu.edu Received September 12, 2013; Accepted September 13, 2013; Published September 19, 2013 Citation: Argyropoulos DS (2013) Towards Thermoplastic Lignin Polymers: Progress in the Utilization of Kraft Lignin for the Synthesis of Heat Stable Polymer Melts. J Biotechnol Biomater 3: e123. doi:10.4172/2155-952X.1000e123 Copyright: © 2013 Argyropoulos DS, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Towards Thermoplastic Lignin Polymers: Progress in the Utilization of Kraft Lignin for the Synthesis of Heat Stable Polymer Melts Dimitris S Argyropoulos 1,2 * 1 Department of Chemistry and Forest Biomaterials, North Carolina State University, Raleigh, NC, USA 2 Most eforts to utilize lignin have been limited by various factors that impart in it characteristics that deine it as an unreliable precursor to polymer production. his is because lignin (and more speciically technical lignin) ofers relatively unpredictable polymerization characteristics, depending upon its source and the degree of deligniication to which the plant materials were subjected. More speciically, the highly functional character of lignin (i.e. rich in phenolic and aliphatic OH groups, as well as reactive benzylic carbons), induces a variety of potential polymerization sites and heat instability in such materials. Both factors promote gelation processes under polymerization conditions or when the temperature increases close to, and/or above the glass transition temperature (Tg). In addition, the relatively low molecular weight (a few thousands) for lignin derived from commercial pulping and bioreinery operations makes lignin unsuitable for higher end applications, such as high performance, heat stable engineering thermoplastic applications. he work of our group at NCSU has focused at providing a detailed molecular understanding of the way the polymeric properties of krat lignin and its derivatives are afected by their thermal treatments. his information was then correlated with the polymeric properties of the materials (glass transition temperature (Tg), molecular weight characteristics, and thermal stability), for a series of selectively and progressively derivatized sotwood krat lignin samples [1]. Sotwood krat lignin was shown to be highly susceptible to thermally induced reactions that cause its molecular characteristics to be severely altered with the concomitant formation of irreversible crosslinking with no thermoplastic processing possibilities. However, by fully methylating the phenolic OH groups [2], from within the structure of sotwood krat lignin, the thermal stability of these materials was seen to be dramatically enhanced and their Tg’s reduced [1]. Optimum thermal stability and melt cycling was observed with the fully methylated derivatives. he accumulated data is aimed at providing the foundations for a rational design of single or multi-component lignin-based thermoplastic materials with reproducible polymeric properties when thermally processed in a number of manufacturing cycles [1-3]. Furthermore, we have been able to create polyarylene (ether sulfone)-krat lignin copolymers synthesized by a base catalyzed stepwise copolymerization of suitably functionalized, fractionated krat lignin with 4,4’-Dilourodiphenyl Sulfone ( DFDPS) in an aprotic solvent at elevated temperatures (Scheme 1) [3]. he beneits of incorporating DFDPS within krat lignin are apparent in the TGA thermograms of the copolymer shown in Figure 1. hermally stable polymer melts exceeding 300°C are apparently attainable [3]. Conclusions and Overall Outlook his efort ofers novel avenues at creating reactive lignin materials that are stabilized and rendered better suited for industrial applications. It provides methods for creating lignins of controlled and modulated characteristics, exhibiting thermal and polymerization stabilities. Such thermal properties and stable molecular weight distributions of lignins and copolymers produced from commercial lignins provides a means for beneicially modulating the properties of an otherwise intractable bio-polymer. References 1. Cui C, Sadeghifar H, Sen S, Argyropoulos DS (2013) Toward thermoplastic Figure 1: TGA of kraft lignin and its DFDPS copolymer. S F F O O Ar OH L DMSO/toluene -H 2 O Ar O - Na + L Ar O - L S F F O O O Ar L - S F F O O O Ar L - S F F O O Ar L O - S F F O O O Ar L - S F O O O Ar L -X - Ar OH L = Lignin molecule with phenolic -OH end group NaOH Scheme 1: Copolymerization of kraft lignin with diluorodiphenylsulfone (DFDPS). Center of Excellence for Advanced Materials Research (CEAMR), King Abdulaziz University, P.O. Box 80203, Jeddah 21589, Saudi Arabia