Highly Efficient Continuous Flow Nanocatalyst Platform Constructed with Regenerable Bacterial Cellulose Loaded with Gold Nanoparticles and a Nanoporous Membrane.

With the development of society and the growing concern about environmental issues, continuous flow catalytic reactors have gained significant interest due to their resource-efficient advantages over traditional batch devices. In this study, we employed a facile one-step in situ reduction approach to construct highly dispersed gold nanoparticles loaded on regenerable bacterial cellulose nanofiber (BCN) heterogeneous catalysts. These catalysts, in combination with a nanoceramic membrane with a pore size of 1 nm, formed a fully mixed system that was favorable for the efficient continuous flow catalysis of selective reduction reactions of nitrophenol. The reaction system demonstrated remarkable catalytic activity toward nitrophenol reduction reactions at low reductant dosages (<5 equiv), achieving over 95% conversion and 99% selectivity for the aniline product in 10 min under room temperature conditions. Furthermore, continuous flow operations maintained stable catalytic activity with minimal catalyst loss after a 120-h test and were 3 times more time-efficient than batch operations. Additionally, continuous monitoring could be conducted through ultraviolet (UV) spectroscopy. A highly efficient and environmentally friendly strategy was present for designing continuous flow reactions in future applications.

Main-Side Chain Hydrogen Bonding-Based Self-Healable Polyurethane with Highly Stretchable, Excellent Mechanical Properties for Self-Healing Acid-Base Resistant Coating.

Developing an autonomous self-healing polyurethane (PU) elastomer with excellent mechanical properties and high ductility has attracted increasing attention. Nowadays, the synthesis of elastomers with excellent mechanical properties and rapid self-healing at room temperature faces a huge challenge. Herein, This work reports a new supramolecular PU with excellent mechanical properties and rapid self-healing at room temperature through the introduction of T-type chain extender into the supramolecular polymer chain. The introduction of T-chain extender can be used to enhance the mechanical strength of PU, and the multiple hydrogen bonds on the side-chain provide theoretical support for the rapid self-healing ability of PU. Maximum stress of the synthesized PU can reach 3.4 ± 0.15 Mpa, and maximum elongation at break can reach 3200% ± 160%. Due to flexibility and re-constructability of side-chain hydrogen bonds, PU stress repair efficiency can reach 96.7%, and can be self-healing scratches rapidly and effectively at room temperature. The mechanical properties and self-healing properties of PU can be adjusted by the content of T-type chain extender. The PU is applied to the metal surface coating, which has excellent acid-base resistance, bond strength up to 2.9 ± 0.1 Mpa, and the ability to eliminate local damage on the coating surface quickly at room temperature.

A new insight into the thermodynamical criterion for the preparation of semiconductor and metal nanocrystals using a polymerized complexing method.

This work reports the intrinsic thermodynamical criterion for the preparation of metal and semiconductor nanocrystals using a polymerized complexing method. The basic principle of this method is the formation of a polymerized complexing structure between mono-, binary-, or ternary-metallic ions and bonding agents in aqueous or ethylene glycol solutions by evaporation of the solvents. Heat treatment of the complexing structure under N2 atmosphere produces H2 and CH4 gases, which can reduce the oxide crystalline nuclei to semiconductor and metallic nanocrystals. Experimental results show that Te, CdTe, Ag2Te, CuTe, NiTe1.5, CoTe1.5, Bi2Te3, Sb2Te3, Bi-Sb, In2Te3, Ni2.9SnTe2, CuGaTe2, and CuInS2 semiconductors and Bi, Sb, Ag, Cu, and Ni metallic nanocrystals can be prepared by this method. Transmission electron microscopy observations show that the obtained Bi, Ag2Te, Bi2Te3, Sb2Te3, CdTe, and NiTe1.5 nanocrystals have grain sizes in the nanometer range. The types of metallic and semiconductor phase that can be obtained by this method are explained by the thermodynamical criterion based on calculations of the Gibbs free energy and electrode potential. It is proposed that the crystalline phase of the final product is controlled by the change of the Gibbs free energies of the reactions of the metal oxide with reducing gases and the metal oxide redox electrode potentials, not the metal redox standard electrode potentials and electronegativities of the elements. Furthermore, a prediction is presented for the preparation of other kinds of binary and ternary compound based on the thermodynamical criterion. Our results provide new insight into facile and green preparation of semiconductor and metal nanocrystals.

Bacterial cellulose nanofiber reinforced self-healing hydrogel to construct a theranostic platform of antibacterial and enhanced wound healing.

In order to promote wound healing, self-healing hydrogels with moisturizing property are employed as wound dressing. In this study, bacterial cellulose nanofibers (BCN) with high mechanical strength are used as reinforcement to improve the mechanical properties of self-healing hydrogels. A multifunctional self-healing hydrogel has been constructed by incorporating natural biomass, including Ag hybrid bacterial cellulose nanofiber (Ag-BCN), resveratrol (Res), and carbon nanodots (CNDs). The results of in vitro experiments demonstrate that the mechanical strength of the hybrid hydrogel was increased by 6 times with the addition of Ag-BCN, which also offers excellent antibacterial efficiency (S. aureus 99.99 % and E. coli 99.68 %). The hydrogel with CNDs can observe the healing process of the crack in real time and realize the controlled release of Res through photothermal effect. Moreover, the results of animal model experiments indicate that the prepared hydrogel could reduce the infection of the wound, effectively shorten the progress of wound healing (from 21d to 14 d). All the results imply that the prepared hydrogel has great promise in the application of skin wound healing.

Polymerized-complex method for preparation of supported bimetallic alloy and monometallic nanoparticles.

Herein, we report a novel polymerized-complex method for the preparation of Ni-Pd, Ni-Pt, and Cu-Pt alloys and Pt, Pd, Ag, Ni, and Cu nanoparticles. The grain sizes and crystalline phases of these nanoparticles can be controlled. These nanoparticles are obtained via the formation of a polymerized complex and release of reducing gases during N2-protected calcination.