Size-controlled synthesis of xylan micro / nanoparticles by self-assembly of alkali-extracted xylan.

Valorization of underutilized biobased feedstocks like hetero-polysaccharides is critical for the development of the biorefinery concept. Towards this goal, highly uniform xylan micro/nanoparticles with a particle size ranging from 400 nm to 2.5 μm in diameter were synthesized by a facile self-assembly method in aqueous solutions. Initial concentration of the insoluble xylan suspension was utilized to control the particle size. The method utilized supersaturated aqueous suspensions formed at standard autoclaving conditions without any other chemical treatments to create the resulting particles as solutions cooled to room temperature. Processing parameters of the xylan micro/nanoparticles were systematically studied and correlated with both the morphology and size of xylan particles. By adjusting the crowding of the supersaturated solutions, highly uniform dispersions of xylan particles were synthesized of defined size. The xylan micro/nanoparticles prepared by self-assembly have a quasi-hexagonal shape, like a tile, and depending upon solution concentrations xylan nanoparticles with a thickness of <100 nm were achieved at high concentrations. Based on the usefulness of polysaccharide nanoparticles, like cellulose nanocrystals, these particles have potential for unique structures for hydrogels, aerogels, drug delivery, and photonic materials. This study highlights the formation of a diffraction grating film for visible light with these size-controlled particles.