Multifunctional cellulosic materials prepared by a reactive DES based zero-waste system.

Energy consumption and post-treatment of chemical reagent residues are important issues that hinder the sustainable production of the natural building blocks of cellulose nanofibrils (CNFs). In this study, we realize a low-energy, zero-waste process for CNF production by designing a novel reactive deep eutectic solvent (DES), the residue of which can be directly used as a plant growth regulator. After pretreatment with the DES, cellulose fibers self-delaminate into thin layers referred to as pseudo-CNFs, as their strength, toughness and transmittance are comparable to those of CNFs. Pseudo-CNFs break into smaller particles during recycling and thus display unique mechanical upcycling. After facile fibrillation, the obtained CNFs can independently form freestanding sub-micrometer films that show a strong, full coloration, which is demonstrated for the first time. Our concept can enable a green process, and the developed cellulosic materials may find various applications as structural materials and optical coatings.

Cellulose or chitin nanofibril-stabilized latex for medical adhesion via tailoring colloidal interactions.

The objective of this research is to develop a functional medical adhesive from natural nanofibril-stabilized latex through an aqueous process. Surface charged cellulose or chitin nanofibrils are used to form Pickering emulsions of acrylic monomers, followed by in situ polymerization. Charged initiators are selected to tailor the interactions between them and nanofibrils, and it is found that the repulsive electrostatic interactions play a key role in stabilizing the heterogeneous system. As a result, poly(2-ethylhexyl acrylate-co-methyl methacrylate) latexes are successfully prepared for surfactant-free adhesives with a high shear strength of 72.0 ± 6.5 kPa. In addition, drug can be easily incorporated in the nanopaper substrate or adhesive layer to form a medical tape, exhibiting long-term drug release and antibacterial behaviors. We managed developing a facile method to integrate green synthesis, versatile functionalities and excellent adhesion into one adhesive, which remains a great challenge.

Surface and Interface Engineering for Nanocellulosic Advanced Materials.

How do trees support their upright massive bodies? The support comes from the incredibly strong and stiff, and highly crystalline nanoscale fibrils of extended cellulose chains, called cellulose nanofibers. Cellulose nanofibers and their crystalline parts-cellulose nanocrystals, collectively nanocelluloses, are therefore the recent hot materials to incorporate in man-made sustainable, environmentally sound, and mechanically strong materials. Nanocelluloses are generally obtained through a top-down process, during or after which the original surface chemistry and interface interactions can be dramatically changed. Therefore, surface and interface engineering are extremely important when nanocellulosic materials with a bottom-up process are fabricated. Herein, the main focus is on promising chemical modification and nonmodification approaches, aiming to prospect this hot topic from novel aspects, including nanocellulose-, chemistry-, and process-oriented surface and interface engineering for advanced nanocellulosic materials. The reinforcement of nanocelluloses in some functional materials, such as structural materials, films, filaments, aerogels, and foams, is discussed, relating to tailored surface and/or interface engineering. Although some of the nanocellulosic products have already reached the industrial arena, it is hoped that more and more nanocellulose-based products will become available in everyday life in the next few years.