Bio-based polymer composites via pickering Emulsions: Xanthated cellulose nanofibers as a dual-function intermediate

Abstract

The uniform dispersion of nanocellulose in polymer matrices remains a challenge in polymer composite fabrication. In this study, we develop a bio-based, surfactant-free approach to prepare polymer composites using xanthated cellulose nanofibers (XCNF) as a dual-function intermediate. XCNF, derived from a modified viscose rayon process, serves as both an emulsion stabilizer and a precursor to regenerated cellulose nanofibers (RXCNF). By stabilizing oil-in-water (O/W) Pickering emulsions containing poly(lactic acid) (PLA) solution, XCNF enables the formation of PLA microsphere latex structures (∼640 nm diameter) upon drying, ensuring intimate proximity between nanofibers and polymer particles. Energy-dispersive X-ray spectroscopy (EDX) confirmed the spontaneous conversion of XCNF into RXCNF, allowing in-situ formation of a reinforcing nanofiber network without additional chemical modifications. The resulting microsphere latex was used as a masterbatch for melt-mixing with PLA to fabricate PLA/RXCNF composites. Differential scanning calorimetry (DSC) revealed enhanced crystallization, while dynamic mechanical analysis (DMA) confirmed a significant increase in storage modulus, particularly beyond the glass transition temperature, demonstrating the reinforcing effect of RXCNF. Additionally, light transmittance measurements showed a progressive reduction in transparency with increasing RXCNF content due to nanofiber-induced light scattering. This approach leverages XCNF as a functional intermediate, providing a scalable and environmentally friendly strategy for bio-based polymer composites with improved performance. With the increasing industrial interest in RXCNF due to its stability and reinforcing potential, this method aligns well with ongoing efforts to commercialize cellulose-based nanomaterials.