A New Analysis of the Depolymerized Fragments of Lignin Polymer Using ToF-SIMS

Abstract

Lignin in plant cell walls is a complex, irregular polymer built from phenylpropanoid C6-C3 units that are connected via various C-C and C-O linkages. A recent study using time-of-flight secondary ion mass spectrometry (ToF-SIMS) with Ga primary ion bombardment showed that lignin polymers can be characterized by specific positive ions possessing a substituted aromatic ring (so-called guaiacyl or syringyl rings), which are the basic building units of lignin. To study the relationship between the characteristic ions of lignin and the common interunit linkages, various lignin dimer model compounds were investigated using ToF-SIMS. The resulting dimer spectra showed that the characteristic ions with a guaiacyl ring at m/z 137 and 151 result from rupture of most common interunit linkages, not only 8-O-4' linkages, which are the most abundant in lignin, but also 8-1', 8-5', and 8-8'. There was no evidence of rupture of 5-5' linkages. These results show that ToF-SIMS offers a new tool for the direct analysis of the depolymerized fragments of lignin polymers. The mechanisms for the fragmentation of lignin dimer models in ToF-SIMS were proposed that allow ToF-SIMS fragmentation rules to be deduced. Adduct ions such as [M + 13]+ ([M + CH]+) were also produced in fragmentation of the dimers and are thought to arise from the combination of the molecules with their stable fragments.

Bio-based Polymer from Ferulic Acid by Electropolymerization

“…Fragment ion I corresponded to the existence of sinapic acid in the reaction medium after electropolymerization. Fragment ion II has also observed by other researchers using TOF-SIMS analysis to analyze a substance produced from enzymatic polymerization of sinapyl alcohol (Saito et al 2005b). Fragment ion II is expected to form by addition of methanol at benzylic position after radical coupling for ring rearomatization (Freudenberg 1965).…”

“…The data provided evidence of the partial structure of the polymer sample. Recently, bio-polymers such as lignin, cellulose and human hair were subjected to the TOF-SIMS analysis to study their structures (Saito et al 2005a(Saito et al , 2005bFardim and Holmbom 2005;Matsushita et al 2008Matsushita et al , 2012Kojima et al 2011). Figure 5 shows the mass spectra of the electropolymerized polymers using ferulic acid, ferulic acid-(methoxy-d3), ferulic acid with the CH2Cl2/CD3OD solvent medium, and caffeic acid.…”

Simulation of SIMS for monomer and dimer of lignin under the assumption of thermal decomposition using QMD method

“…By considering the thermal decomposition, we are able to simulate the decomposition of the monomer and dimer of lignin by QMD method in order to compare with experimental results of SIMS. 20,21 As an example of data, Fig. 1 shows the snap shots of the thermal decomposition of the dimer at 0, 2000, and 4000 steps with 0.78 eV energy control using semiempirical AM1 method.…”

Multivariate Analysis Applied to Polymer Imaging Data Obtained by Near-Field Infrared Microscopy

“…There are several basic techniques that have been applied to chemical imaging. For example, mass imaging, including secondary ion mass spectrometry [1][2][3][4][5], is one of the most powerful imaging techniques because it provides detailed images with high spatial resolution of approximately 100 nm using time-of-flight secondary ion mass spectrometry (TOF-SIMS) [1]. Spectroscopy techniques such as infrared (IR) spectroscopy [6,7] are also useful for obtaining imaging and chemical structure information.…”