Lignosulfonate/silica hybrid nanoparticles as a novel biobased filler in polybenzoxazine matrix

Lignin is an abundant and sustainable resource that exhibits numerous attractive functional properties as a reinforcing agent for benzoxazine-based composites, due to its stiffness, thermal stability, and high carbon content. However, the low quality of lignin particles dispersions associated with the weak particles-matrix interactions reduces the reinforcement capability. In this work, hybrid lignin/silica (NaLS/SiO₂) nanoparticles were obtained from sodium lignosulfonate (NaLS) and tetraethylorthosilicate (TEOS) under basic conditions. The particles were characterized by transmission electron microscopy (TEM) confirming their spherical morphology and narrow nanometric-size distributions. The hybrid particles were incorporated into conventional benzoxazine (BA-a) and a difuran biobased benzoxazine (SA-dfda) to prepare nanocomposites with different mass compositions (3, 5, and 10 wt%). Morphological, mechanical, dynamo-mechanical, and thermal properties of the obtained composites were assessed. All the materials exhibited a homogenous filler dispersion that contributed to improve the reinforcement properties. Hybrid nanoparticles proved to be an interesting alternative as a filler in the benzoxazine matrix to prepare high-performance thermosetting composites.