Solid-state NMR as a Powerful Tool to Characterize Polysaccharide-based Systems

Download or read book Solid-state NMR as a Powerful Tool to Characterize Polysaccharide-based Systems written by Francesco D'Acierno and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: An accurate structural characterization of polysaccharide-based systems is crucial in understanding the properties of the materials. Among all the characterization techniques, solid-state NMR spectroscopy proves to be fundamental for a clear picture of complex polysaccharide-based systems. An example of complexity in these systems is represented by disordered structures. Polysaccharides with large fractions of amorphous regions can be analyzed using 1H-13C cross-polarization (CP) magic-angle-spinning (MAS) to resolve their molecular sites. The same experiment can be applied to biochars obtained by thermal degradation of biopolymers to quantitatively characterize the forms of carbon present, in combination with direct polarization (DP) MAS to determine the size of the carbonaceous char clusters. Solid-state NMR is also effective in the structural characterization of porous materials. Some polysaccharides, such as chitin, self-assemble in mesoporous architectures directly in nature, while for others, such as cellulose, reduction to a nanocrystalline form is required to obtain these types of networks. Mesoporous polysaccharide-based materials can often be used as templates to create inorganic materials with complementary porosity, such as alumina aerogels, which can be exploited as catalyst supports, absorbents, or thermal insulators. Solid-state NMR enables the structural characterization of the biotemplated materials, when the corresponding isotope is NMR-sensitive. In this presentation, I will discuss our use of solid-state NMR techniques to probe the structures of new materials developed from biopolymers. This technique gives insight into the structure of the materials that is not available from other analytical methods.