Development of PLA/PMMA/regenerated cellulose nanofiber composites via Pickering emulsion-derived masterbatch approach

A major challenge in the development of polymer composites lies in the inherent incompatibility between hydrophilic cellulose nanofibers (CNF) and hydrophobic polymer matrices. This study explores the fabrication of poly(methyl methacrylate) (PMMA) composites through Pickering emulsion method stabilized by xanthated cellulose nanofibers (XCNF), aiming to improve the dispersion and morphological control of CNF in hydrophobic polymer systems. The oil-in-water Pickering emulsion remained stable for 24 h, confirming the ability of XCNF to effectively stabilize the emulsion without the use of synthetic surfactants. As previous studies revealed that xanthate group gradually decomposed at ambient temperature, thus, after drying, XCNF was assumed to be converted into regenerated cellulose nanofibers (RXCNF). PMMA/RXCNF composites were characterized using Fourier transformed – infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). FTIR revealed characteristic peaks attributed to RXCNF, indicating successful incorporation of RXCNF within PMMA. Meanwhile, SEM micrographs showed adsorption of RXCNF in the PMMA surface indicating successful dispersion of CNFs within PMMA through the formation of microspheres. The PMMA/RXCNF composite was then utilized as a carrier system in the preparation of PLA composites by melt-mixing using a batch-type kneader, allowing for effective dispersion of RXCNF into PLA matrix. Dynamic mechanical analysis (DMA) of PLA/PMMA/RXCNF composites showed an increase in the storage modulus at 25 °C, from 2294 MPa (neat PLA) to 3044 MPa (0.5% RXCNF), and decrease in the tan δ peak for composites with RXCNF, indicating that Pickering emulsion-derived microspheres allow better dispersion of RXCNF in the PLA matrix under shear during melt-mixing. These results highlight the potential of Pickering emulsion-derived PMMA/RXCNF microspheres as an efficient “carrier system” for achieving uniform nanofiber dispersion in polymer composites, offering a strategy for the development of bio-based materials.