Robust cellulose nanofibrils reinforced poly(methyl methacrylate)/polystyrene binary blend composites with pebble-shaped structure using Pickering emulsion gel

Both poly(methyl methacrylate) (PMMA) and polystyrene (PS) have excellent transparency, but a blend of the two typically has low mechanical properties and poor transparency owing to phase separation. Herein, oil-in-water Pickering emulsion gel technology was combined with the hot pressing process to prepare cellulose nanofibrils (CNFs) reinforced PMMA/PS binary blend composite film materials (CNFs/PMMA/PS). The CNFs/PMMA/PS composites with a pebble-shaped structure had a unique three-dimensional crosslinked network structure and endowed the composite film with better thermal stability, and excellent transparency and mechanical properties. Particularly, the derivative thermogravimetry and differential scanning calorimetry results revealed that the compatibility between the PMMA and the PS phases in the composite film is remarkably improved. The optimal tensile strength (58 MPa) and maximum strain (4.2%) were obtained when the content of CNFs was 52%, which represented approximately 3-fold and 2-fold improvements, respectively, than those of the PMMA/PS blend films. Moreover, the C-CNFs/PMMA/PS composite films maintained an excellent light transmittance of approximately 80% in the wavelength range of 600 to 800 nm. The facile preparation method is proposed to achieve an excellent dispersion of unmodified CNFs in hydrophobic and binary polymer mixture, which constitutes a new approach for using CNFs to enhance the high performance of polymer materials.