Lignin, the most abundant aromatic renewable biopolymer in nature, has a unique pH-stimuli-responding property, which has long been used in the dissolution and precipitation of lignin in the traditional pulp and paper industry, though it has not gained appropriate attention for other applications. Based on its unique solubility, lignin hydrogel and nanoparticles have been developed. (i) All-lignin-based hydrogel (Lig-gel) with excellent pH-stimuli-responsive performance was synthesized by the one-step crosslinking reaction of industrial kraft lignin with poly(ethylene glycol) diglycidyl ether. Lig-gel exhibited excellent actuating performance alternating between softening/enhancement and straight/bending shapes. The alternation cycle can be completed in just 1 min and repeated many times. Applying these properties, a smart hook and a flow control valve were developed to hook objects and control the filtration of the solution, respectively. (ii) A green approach to producing super long-term stable lignin nanoparticles (LTSL NPs). LTSL NPs were prepared directly from black liquor via an acid precipitation method. LTSL NPs exhibited well uniformity, excellent dispersibility, controllable size, and super long-term stability in aqueous media (no apparent size increase or any particle precipitation for 90 days in neutral water medium). In addition, the sizes can be well controlled by tuning the degree of acid precipitation (the final pH value). These new findings will open a new field for not only functional materials but also lignin valorization.

Development of lignin hydrogel and nanoparticles based on its pH-sensitivity

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.