Lignins are biologically based polymers with very non-linear structures. These complex polymers are found in the secondary cell walls in plants and, with subsequent treatment, can be used as a starting material for many industrially relevant chemicals. Pulsed-field gradient nuclear magnetic resonance (PFG-NMR) was used to collect experimental molecular diffusion data on solutions for a variety of different lignins, both commercially available and processed from non-traditional sources. The PFG-NMR signal attenuation during the diffusion experiments were then mathematically analyzed assuming a gamma distribution of diffusion constants, or through an inverse Laplace transform (ILT). As a final step, the distribution of the measured diffusion constants was mapped to a molecular weight domain. The PFG-NMR method of ascertaining molecular weights has the benefit of being quick compared to the more traditional column fractionation. Therefore, using PFG-NMR should be the preferred method for obtaining molecular weights of lignin samples in many experimental situations.

Exploring the use of pulsed field gradient (PFG) NMR to extract molecular weight distributions of lignin

249th National Meeting (2015)

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