Xanthated cellulose nanofibers dispersion: Stability, pickering emulsion with styrene, and latex composite via polymerization

Abstract

Leveraging xanthated cellulose nanofibers (XCNF) from a modified rayon process, this study explores their use as stabilizers in Pickering emulsion polymerization for nanocomposite production. XCNF was produced from softwood pulp through a xanthation process that utilized a reduced NaOH concentration of 8.5 %, lower than the typical rayon process, and was followed by mechanical defibrillation, resulting in fiber widths under 10 nm. Following the protective allylation of xanthate groups and hydrophobic modification, 1H NMR analysis was conducted, revealing a xanthation degree of 0.144. When stored at 4 °C, a 0.5 wt% XCNF dispersion gelled by the fifth day, as confirmed by visual and rheological assessments. UV and TEM analyses indicated xanthate detachment and nanofiber aggregation over time, respectively. The addition of a low-temperature initiator to the XCNF-stabilized styrene-water emulsion enabled polymerization, yielding nanofiber-encapsulated polystyrene latex. This led to transparent sheets upon thermal pressing, demonstrating the potential of XCNF in developing polymer nanocomposites.