Conventional metal-organic framework (MOF) powders have periodic micro/mesoporous crystalline architectures tuned by their three-dimensional coordination of metal nodes and organic linkers. To add practical macroscopic shapeability and extrinsic hierarchical porosity, fibrous MOF aerogels were produced by synthesizing MOF crystals on the template of TEMPO-cellulose nanofibrils. Cellulose nanofibrils not only offered extrinsic porosities and mechanical flexibility for the resultant MOF aerogels, but also shifted the balance of nucleation and growth for synthesizing smaller MOF crystals, and further decreased their aggregation possibilities. Thanks to their excellent shapeability, hierarchical porosity up to 99%, and low density below 0.1 g/cm, these MOF aerogels could make the most of their pores and accessible surface areas for higher adsorption capacity and rapid adsorption kinetics of different molecules, in sharp contrast to conventional MOF powders. Thus, this scalable and low-cost production pathway is able to convert MOF powders into a shapeable and flexible form and thereby extend their applications in more broad fields, for example, adapting a conventional filtration setup.

Magnetic hybrid hydrogels with a novel polymeric coating consisting of chitosan and cellulose were prepared. By coating cellulose and chitosan, we combined the renewability and biocompatibility of cellulose and chitosan as well as the magnetic properties of Fe(3)O(4) to create a hybrid system to adsorb heavy metals.

In this work, a sustainable and green process to prepare nanocrystalline cellulose (NCC) from bleached hardwood pulp was demonstrated. Rod-like nanocrystalline cellulose with the size of 15-40 nm in width and hundreds of nanometers in length was obtained through H3PW12O40 (HPW)-catalyzed hydrolysis of bleached pulp fibers under the mild reaction conditions. Thermogravimetric analysis revealed that the resulting NCC exhibited much higher thermal stability than the partially sulfated NCC (prepared by sulfuric acid). In addition, the concentrated HPW could be easily recovered and recycled through the extraction with diethyl ether, and the recovered HPW could be reused for several rounds of cellulose hydrolysis without activity lost. These fundamental studies are of crucial importance for the development and application of NCC products/NCC-based biomaterials with good thermal stability.

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Modification of sodium lignosulfonate (SLS) via combined oxidationsulfomethylation was employed to prepare concrete superplasticizer. It was found that the oxidation of SLS by peroxyacetic acid facilitated the subsequent sulfomethylation. After modification, both the molecular weight and sulfo group content were significantly increased, and thus the performance of SLS as water reducer was improved. With the water to cement ratio at 0.4 and 0.3% (w/w) modified SLS, the fluidity of cement paste could reach 185 mm, which was 15% higher than that with unmodified SLS. It was also comparable to the performance of commercial naphthalene superplasticizer under the same conditions.

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Abstract:Recently, the rapid emergence of antibiotic-resistant pathogens has caused a serious health problem. Scientists respond to the threat by developing new antimicrobial materials to prevent or control infections caused by these pathogens. Polymer-based nanocomposite hydrogels are versatile materials as an alternative to conventional antimicrobial agents. Cross-linking of polymeric materials by metal ions or the combination of polymeric hydrogels with nanoparticles (metals and metal oxide) is a simple and effective approach for obtaining a multicomponent system with diverse functionalities. Several metals and metal oxides such as silver (Ag), gold (Au), zinc oxide (ZnO), copper oxide (CuO), titanium dioxide (TiO 2 ) and magnesium oxide (MgO) have been loaded into hydrogels for antimicrobial applications. The incorporation of metals and metal oxide nanoparticles into hydrogels not only enhances the antimicrobial activity of hydrogels, but also improve their mechanical characteristics. Herein, we summarize recent advances in hydrogels containing metal ions, metals and metal oxide nanoparticles with potential antimicrobial properties.