Comparison of nanocrystalline cellulose and fumed silica in latex coatings

Exploratory work has been undertaken to compare the performance of nanocrystalline cellulose (NCC) with fumed silica in styrene/acrylic latex coatings. NCC has emerged as a promising candidate for the reinforcement of polymeric materials because of its impressive mechanical properties and renewable nature. However, a better understanding of NCC in nanocomposites, compared to more conventional fumed silica-filled systems, is critical to identify feasible commercial applications for NCC. While the dispersion of nanomaterials in polymer matrices is often a challenge, by working with hydrophilic nanoparticles in a waterborne latex, the authors demonstrate that both NCC and fumed silica were dispersed in the latex coatings (up to 9 wt% loadings). The hardness, elastic modulus, resistance to plastic deformation and impact strength were similar for coatings with both types of nanomaterials at loadings below the percolation threshold of NCC (~3 wt%); however, the mechanical performance of NCC-filled coatings was significantly better at higher loadings. In abrasion and corrosion resistance tests, NCC-filled coatings underperformed relative to unfilled and fumed silica-filled coatings. This is the first report that directly compares NCC-filled polymeric coatings with silica-filled coatings including evaluation using industry standards like nanoindentation and corrosion resistance testing. This article contains supporting information that will be made available online once the issue is published.