Ionic Liquid-Based Route for the Preparation of Catalytically Active Cellulose–TiO2 Porous Films and Spheres

Production and Surface Modification of Cellulose Bioproducts

Petroleum-based synthetic plastics play an important role in our life. As the detrimental health and environmental effects of synthetic plastics continue to increase, the renewable, degradable and recyclable properties of cellulose make subsequent products the "preferred environmentally friendly" alternatives, with a small carbon footprint. Despite the fact that the bioplastic industry is growing rapidly with many innovative discoveries, cellulose-based bioproducts in their natural state face challenges in replacing synthetic plastics. These challenges include scalability issues, high cost of production, and most importantly, limited functionality of cellulosic materials. However, in order for cellulosic materials to be able to compete with synthetic plastics, they must possess properties adequate for the end use and meet performance expectations. In this regard, surface modification of pre-made cellulosic materials preserves the chemical profile of cellulose, its mechanical properties, and biodegradability, while diversifying its possible applications. The review covers numerous techniques for surface functionalization of materials prepared from cellulose such as plasma treatment, surface grafting (including RDRP methods), and chemical vapor and atomic layer deposition techniques. The review also highlights purposeful development of new cellulosic architectures and their utilization, with a specific focus on cellulosic hydrogels, aerogels, beads, membranes, and nanomaterials. The judicious choice of material architecture combined with a specific surface functionalization method will allow us to take full advantage of the polymer's biocompatibility and biodegradability and improve existing and target novel applications of cellulose, such as proteins and antibodies immobilization, enantiomers separation, and composites preparation.

Development of Diallylimidazolium Methoxyacetate/DMSO (DMF/DMA) Solvents for Improving Cellulose Dissolution and Fabricating Porous Material

Cellulose is the most abundant natural biopolymer, with unique properties such as biodegradability, biocompability, nontoxicity, and so on. However, its extensive application has actually been hindered, because of its insolubility in water and most solvents. Herein, highly efficient cellulose solvents were developed by coupling diallylimidazolium methoxyacetate ([A₂im][CH₃OCH₂COO]) with polar aprotic solvents dimethyl sulfoxide (DMSO), N,N-dimethylformamide (DMF), and N,N-dimethylacetamide (DMA). Attractively, these solvents showed extraordinarily powerful dissolution performance for cellulose (e.g., 26.1 g·100g⁻¹) in [A₂im][CH₃OCH₂COO]/DMSO(R_DMSO = 1.01 solvent even at 25 °C), which is much more advantageous over previously reported solvents. To our knowledge, such powerful cellulose solvents have not been reported before. The cellulose dissolution mechanism is proposed to be of three combined factors: (1) The hydrogen bond interactions of the H2, H4 and H6 in [A₂im]⁺ and the carboxyl O atom in [CH₃OCH₂COO]⁻, along with the hydroxyl H atom and O atom in cellulose, are main driving force for cellulose dissolution; (2) the dissociation of [A₂im][CH₃OCH₂COO] by DMF increases the anion and cation concentrations and thus promotes cellulose dissolution; (3) at the same time, DMF also stabilizes the dissolved cellulose chains. Meanwhile, the porous cellulose material with a varying morphologic structure could be facially fabricated by modulating the cellulose solution concentration. Additionally, the dissolution of cellulose in the solvents is only a physical process, and the regenerated cellulose from the solvents retains sufficient thermostability and a chemical structure similar to the original cellulose. Thus, this work will provide great possibility for developing cellulose-based products at ambient temperatures or under no extra heating/freezing conditions.