Manipulating Lignin Solubility

Lignin, a byproduct of many cellulosic processing techniques, is the second most abundant renewable resource after cellulose.  As a branched, natural polymer based on aromatic moieties, lignin has the potential to be useful in a number of polymeric applications such as bio-derived filler in polymer composites.  Unfortunately, lignin is insoluble in a number of organic solvents and polymer systems, limiting many industrial applications.  This work explores chemical modifications to lignin for the purposes of increasing the lignin solubility in several widely used solvents.  Specifically, a two-step process has been explored where lignin is esterified, then nitrated.  Proper manipulation of this process allows for the solubility of lignin to be pushed in either the polar or non-polar direction.  Additionally, the esterification can be used to incorporate a number of chemical moieties.  This poster will present work on determining the Hildebrand solubility parameters for modified lignins, with a systematic look at how each chemical modification alters the solubility parameters.