The transition from the current fossil-based economy to a sustainable bio-based economy requires utilization of renewable materials from natural sources, which are often complex and heterogeneous. Their macromolecular features i.e. molar mass, size, and conformation provide an insight on their structure-function relationships. Often, functionality is a result of complex macromolecular features, whose understanding requires detailed characterization. However, the macromolecular characterization is often limited to conventionally employed size-exclusion chromatography (SEC). The limitations within SEC are largely overcome by asymmetric flow-field-flow fractionation (AF4).<br/><br/>We studied the macromolecular features of softwood galactoglucomannan (GGM) -rich pressurized-hot water extract, without purification and after a subsequent ethanol-precipitation to remove monomers, oligomers, and the majority of non-carbohydrate residues. First, the AF4 method was optimized for efficient fractionation of multiple size classes of the extract. Secondly, the molar mass, size, and conformational properties of the fractionated classes were analyzed by coupling the AF4 with a multi-angle light scattering detector (MALS). The conformational insight obtained from AF4-MALS was further validated by small-angle X-ray scattering (SAXS) and cryo-transmission electron microscopy (Cryo-TEM).<br/><br/>Our results showed that both types of GGM extract were heterogeneous. In addition to low-molar mass polysaccharide fractions, colloidal entities in the form of assemblies, and/or particles were present. The results were supported by MALS and SAXS, and the entities were visualized by Cryo-TEM. From our optimized AF4 method, it was possible to fractionate multiple size-classes of GGM extract in one experimental run, which, otherwise is very challenging. The AF4 method will be helpful for the characterization of complex wood extracts, or in general, heterogeneous samples with multiple size classes. The study provides a valuable understanding of the unique macromolecular features of GGM-rich extracts, which is highly beneficial for utilizing them as a novel, bio-based materials in different applications, for example, as Pickering stabilizer particles.

Colloidal features of softwood extracts

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.