Yuan Tong

Solvothermal synthesis of flower-like CoS hollow microspheres with excellent microwave absorption properties

In this study, flower-like CoS hollow spheres (CHSs), synthesized via a facile solvothermal method in the presence of CTAB, were initially investigated as microwave absorbers. It was found that such microstructure was significantly different from CoS nanoparticles (CoS NPs) prepared without introducing CTAB under similar preparation conditions. Moreover, with a low filler loading of 20 wt%, CHSs based composite could reach an optimal reflection loss of −43.6 dB at 15.6 GHz, and exhibit an effective absorption bandwidth (below −10 dB) of 4.6 GHz (13.2–17.8 GHz) at the thin thickness of 2.0 mm. Furthermore, through adjusting the thickness from 2.0 to 5.0 mm, an effective absorption bandwidth of 13.2 GHz could be monitored in the frequency range of 4.8–18.0 GHz. The results indicate that the novel CHSs are intriguing microwave absorbers with the advantages of strong absorption, broad bandwidth, light weight and thin thickness, which is attributed to the unique nanoarchitecture, extra void space, and high dielectric loss.

Enhanced mechanical properties of silica nanoparticle-covered cross-linking graphene oxide filled thermoplastic polyurethane composite

In this work, silica nanoparticle-covered cross-linking graphene oxide (GOES) was successfully synthesized in a stacking graphene oxide (GOE) solution where ethylenediamine (EDA) was used for simultaneous reduction and functionalization of the graphene oxide (GO). The GOES-filled thermoplastic polyurethane (TPU) composites were prepared through solution mixing and the mechanical properties of GOES/TPU were systematically investigated. The results revealed that the properties of composites filled with the cross-linked (GOE, GOES) filler are better than those of un-cross-linked (GO, GOS) filler. Furthermore, with a loading of 2 wt%, the tensile strengths and the tensile strains of GOES/TPU composites were significantly enhanced (48.9 MPa, 2140%), as compared to pure TPU (30.6 MPa, 1370%). The improvement in mechanical properties of GOES/TPU is attributed to the homogeneous dispersion of GOES in the TPU matrix and the strong interfacial interactions between them.

Synthesis of Amphiphilic Copolymers Containing Ciprofloxacin and Amine Groups and their Antimicrobial Performances Revealed by CLSM and AFM

Two series of amphiphilic antimicrobial copolymers containing ciprofloxacin (CPF) and amine functional groups have been synthesized via free-radical copolymerization. The chemical structures of the different amine groups and the copolymer compositions have been systematically varied to study how the structure of the copolymer exerts an influence on the antibacterial activity. The viability of Escherichia coli in the presence of antimicrobial copolymers was observed by confocal laser-scanning microscopy (CLSM). CLSM as well as atomic-force microscopy (AFM) were applied to visualize changes in morphology of bacteria treated with antimicrobial copolymers and elucidate the antimicrobial mechanism of the antimicrobial copolymers. Morphological changes of bacteria observed via AFM and CLSM demonstrated that the antibacterial mechanism was due to the disruption of the bacterial membrane. The destruction of the cell membrane was also confirmed by the leakage of intracellular components, which had a strong absorbance at 260 nm. The inhibitory process was monitored by UV absorption dynamically.