Lignin supracolloids synthesized from (W/O) microemulsions: use in the interfacial stabilization of Pickering systems and organic carriers for silver metal.

Taking advantage of the aromatic and cross-linking tendency of lignin macromolecules extracted from plants, we present a novel method for their assembly into supracolloidal structures. Specifically, spherical particles with controllable size (∼90 nm to 1 μm) were obtained from water-in-oil (W/O) microemulsions formulated with a mixture of nonionic surfactants and a colloidal dispersion of a low molecular weight alkali lignin. After spontaneous emulsification, the internal lignin-rich phase was cross-linked to produce the solid particles that could be easily separated by removal of the organic, continuous phase. The efficiency of the fractionated lignin particles to stabilize hexadecane-in-water Pickering emulsions was demonstrated and their properties were compared against those obtained by using traditional inorganic particles. The effect of the particle size of lignin on the emulsion structure is discussed. As a proof of concept we further introduce the use of related emulsions to enable in situ reduction of silver and loading of silver nanoparticles in lignin carriers.