Spatioselective surface chemistry for the production of functional and chemically anisotropic nanocellulose colloids

Maximizing the benefits of nanomaterials from biomass requires unique considerations associated with their native chemical and physical structure. Both cellulose nanofibrils and nanocrystals are extracted from cellulose fibers via a top-down approach and have significantly advanced materials chemistry and set new benchmarks in the last decade. One major challenge has been to prepare defined and selectively modified nanocelluloses, which would, e.g., allow optimal particle interactions and thereby further improve the properties of processed materials. At the molecular and crystallite level, the surface of nanocelluloses offers an alternating chemical structure and functional groups of different reactivity, enabling straightforward avenues towards chemically anisotropic and molecularly patterned nanoparticles via spatioselective chemical modification. In this review, we will explain the influence and role of the multiscale hierarchy of cellulose fibers in chemical modifications, and critically discuss recent advances in selective surface chemistry of nanocelluloses. Finally, we will demonstrate the potential of those chemically anisotropic nanocelluloses in materials science and discuss challenges and opportunities in this field.Peer reviewe

Effect of cationic and anionic surfactants on the application of calcium carbonate nanoparticles in paper coating

Modification of calcium carbonate particles with surfactant significantly improves the properties of the calcium carbonate coating on paper. In this study, unmodified and CTAB (hexadecyltetramethylammonium bromide)- and oleate-modified calcium carbonate nanoparticles were prepared using the wet carbonation technique for paper coating. CTAB (cationic surfactant) and sodium oleate (anionic surfactant) were used to modify the size, morphology, and surface properties of the precipitated nanoparticles. The obtained particles were characterized using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, zeta potential measurements, thermal gravimetric analysis (TGA), and transmission electron microscopy (TEM). Coating colors were formulated from the prepared unmodified and modified calcium carbonates and examined by creating a thin coating layer on reference paper. The effect of calcium carbonate particle size and surface modification on paper properties, such as coating thickness, coating weight, surface roughness, air permeability, brightness, whiteness, opacity, and hydrophobicity, were investigated and compared with commercial ground (GCC) calcium carbonate-coated papers. The results show that the obtained calcium carbonate nanoparticles are in the calcite phase. The morphology of the prepared calcium carbonate nanoparticles is rhombohedral, and the average particle diameter is less than 100 nm. Compared to commercial GCC, the use of unmodified and CTAB- and oleate-modified calcium carbonate nanoparticles in paper coating improves the properties of paper. The highest measured paper properties were observed for paper coated with oleate-modifed nanoparticles, where an increase in smoothness (decrease in paper roughness) (+23%), brightness (+1.3%), whiteness (+2.8%), and opacity (+2.3%) and a decrease in air permeability (-26%) was obtained with 25% less coat weight. The water contact angle at a drop age time of 10 min was about 112 for the paper coated with oleate-modified nanoparticles and 42 for paper coated with CTAB-modified nanoparticles compared to 104 for GCC-coated paper. © 2014 American Chemical Society.SCOPUS: ar.jSCOPUS: ar.jinfo:eu-repo/semantics/publishe

Hybrid nanocomposites through colloidal interactions between crystalline polysaccharide nanoparticles and oxide precursors

International audienceThis chapter is devoted to the presentation of hybrid nanocomposite materials obtained through the interaction of colloidal crystalline polysaccharides and precursors of oxide phases. It also includes a preliminary introduction to the chemistry and physical chemistry of the polysaccharide nanocrystals, mainly cellulose and chitin. The main approaches and processes employed for the synthesis of the nanocomposites are described for different oxide families: silica, transition metals and metal oxides, phosphate and carbonate phases, and graphene oxide. Additionally, the properties of the materials are mentioned, and described in more details when they result from a combination of polysaccharide and oxide phases (typically for mechanical and optical properties). Globally, this chapter aims at giving a comprehensive review of the innovating research undertaken in the field and providing starting knowledge for nonspecialist readers