Muyang Zhang

Synthesis and characterization of porous fibers/polyurethane foam composites for selective removal of oils and organic solvents from water

In the field of oil/water separation, functional oil-absorbing materials with both controllable porous structures and swelling properties are highly desirable. In the present study, we report a novel strategy for fabricating Mg–Al porous fiber (Mg–Al PF)/polyurethane (PU) foam composites using a combined biotemplate method and foaming technology, and discuss their application in the absorption of oils and organic solvents. The Mg–Al PF composites with a hierarchical porous structure are fabricated based on nanoplatelets on the surfaces of microscale inorganic fibers. The PU foam composites with excellent oil swelling properties are synthesized by addition of Mg–Al PF composites to PU foams. In order to enhance the hydrophobic and oleophilic properties, the surfaces of Mg–Al PF composites are chemically modified using silane coupling agent (KH 570). The surface modified Mg–Al PF composites show high repellency towards water with a water contact angle of 146.6°. Owing to their unique pore structures and superhydrophobic and swelling properties, the foam composites can remove oils and organic solvents from water with high selectivity and absorption capacity, and can absorb not only floating oil but also heavy organic solvents underwater. In general, the absorption capacities of the PU foam composites for oils and organic solvents are 5.06–44.81 times their own weight, partly depending on the density and viscosity of the absorbate. The PU foam composites still maintain relatively consistent absorption properties for oil and organic solvent absorption after 10 cycles. These outstanding properties potentially make the as-prepared PU foam composites promising candidates for practical oil absorption and oil/water separation.

Novel design, facile synthesis and low infrared emissivity properties of single-handed helical polysilanes

The novel single-handed helical polysilanes (HPS), poly[di-n-hexylsilane-co-(methoxycarbonyl ethyl propyl ether)methylsilane] were synthesized by the Wurtz-type coupling of the chiral functional monomer, dichloro(methoxycarbonyl ethyl propyl ether)methylsilane (DCMMS). The monomer was prepared by the hydrosilylation reaction of methyl (S)-2-(allyloxy)propanoate. The chemical structure of HPS was confirmed by 1H, 13C and 29Si nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FT-IR), ultraviolet-visible spectroscopy (UV-Vis) and circular dichroism (CD). The weight distributions and crystallinity of the polysilanes were demonstrated by gel permeation chromatography (GPC), differential scanning calorimetry (DSC) and polarized light microscopy (POM), respectively. The single-handed helical characterization and polymerization degree of the new-typed polysilanes could be controlled by the co-monomers of DCMMS and di-n-hexyldichlorosilane (DCDHS), respectively. Furthermore, the infrared emissivity values (0.598 at 8–14 μm) of HPS were investigated by an Infrared Emissometer.

Helical polysilane wrapping onto carbon nanotube: preparation, characterization and infrared emissivity property study

A helical polysilane/multi walled carbon nanotubes composite was fabricated by wrapping helical HPS copolymer around the surface of modified nanotubes through surface oxidation. HPS was pre-polymerized by Wurtz-type coupling reaction in chloroform (CHCl3), demonstrating optical activity and adoption of a predominately signal-handed helical conformation. Various kinds of characterization including Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV-vis), thermogravimetric analysis (TGA), circular dichroism (CD) and Raman spectroscopy have been utilized to demonstrate HPS noncovalently wrapped around the nanotubes to protect their original graphite structure. The wrapped HPS exhibited enhanced thermal stability and increased optical activity after wrapping. The infrared emissivity property of the composites at 8–14 μm was investigated as well. These results indicate the HPS/f-MWNTs composites possess a much lower infrared emissivity value (e = 0.576) than raw MWNTs, which resulted from synergistic effect of the particular helical conformation of HPS and improved interfacial interaction between the organic polymers and inorganic nanoparticles.

Laterally-uniform Mn3O4 colloidal nanosheets: oriented growth and size-controlled synthesis

In this work, laterally-uniform Mn3O4 nanosheets with regular square-like shapes and tunable lateral dimensions are synthesized through an effective one-pot solvothermal chemical reaction. The formation pathway of the Mn3O4 nanosheets and sized-controlled methods are also investigated.