Surface modified cellulose nanocrystals for tailoring interfacial miscibility and microphase separation of polymer nanocomposites

High performance nanocomposites with good interfacial miscibility and phase separated morphology have received a lot of attention. In this work, cellulose nanocrystals (CNCs) were first grafted with hydrophobic poly(methyl methacrylate) (PMMA) chains to produce modified CNCs (PMCNCs) with increased thermal stability. Such surface-tailored CNCs effectively influenced the phase morphology and improved the mechanical properties of poly(butyl acrylate-co-MMA) (PBA-co-PMMA) nanocomposites. Morphological analysis indicated the presence of microphase separation in PMCNCs/PBA-co-PMMA nanocomposites with PBA as the soft domain and PMMA as well as CNCs as the hard domain. The nanocomposites with 10 wt% PMCNCs/PBA-co-PMMA showed increases in Young’s modulus of more than 20-fold and in tensile strength of about 3-fold compared to those of the unmodified PBA-co-PMMA copolymer. Therefore, the PMCNCs played a crucial role in controlling the interfacial miscibility and tuning the phase morphology of the nanocomposites. It is also essential to understand the role played by microphase separation in achieving nano-scaled morphological control and in fine-tuning the resultant composite properties. Graphical abstract