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

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.