Preparation of lignin nanoparticles by chemical modification

Lignin is the main natural aromatic polymer and consists of about a quarter of lignocellulosic biomass. That is why products obtained from lignin are very attractive research topics, but it is also a very complex issue due to its complicated structure which depends on the separation method and plant species. To become a widely used raw material, the basic characteristics and structure-dependent properties must be elucidated, initially. For this reason, it is necessary to obtain lignin with superior properties, to be able to compete with fossil resources. This paper presents a chemical method to modify lignin by hydroxymethylation to obtain nanoparticles. Nanotechnology allows using chemical, physical and biological effects that do not occur outside the nanoscale world. To find the best conditions (from the average particle size distribution point of view), three reaction parameters were varied: ratio of lignin/aldehyde, pH and temperature. The following output value has been the average particle size distribution. The obtained data were processed with software in demo version (Modde 9) and resulted regression equation allows us to establish the optimum conditions. At the same time, the reaction products thus synthesized were characterized by FTIR spectroscopy, GPC, and (PNMR)-P-31 spectroscopy. The results confirm that using this reaction, it is possible to synthesize nanoparticles from hydroxymethylated lignin. Lignin derivatives containing high hydroxyl group content have a potential utilization as phenol substitute in the phenol formaldehyde resin synthesis, composites, biocides, etc.