Size-Controlled and Super Long-Term Stable Lignin Nanospheres through a Facile Self-Assembly Strategy from Kraft Lignin.

In diverse fields, much attention has been concentrated on the preparation of lignin nanospheres with various structures. Here we report a facile self-assembly strategy for preparing super long-term stable hollow and solid nanospheres based on lignin fractionation. We found that different lignins obtained at different pHs during fractionation can form nanospheres with different particle sizes and structures. The self-assembled and formation mechanisms of the nanospheres were surveyed by dynamic light scattering (DLS), elemental analysis, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The analysis results showed that the phenolic hydroxyl groups and the intermolecular π-π interaction play a decisive effect in the formation of nanospheres. This study can not only facilitate the advance of lignin-based nanotechnologies but also provide a broad prospect for the use of black liquor.