•N-POSS-substituted PBI bearing POSS pendant moieties were synthesized.•The POSS pendant moieties break PBI intermolecular face-to-face packing and hydrogen bonding.•N-substitution with POSS in the rigid backbone improve the solubility of PBI.•Grafted POSS enhance mechanical properties of PBI.A series of N-POSS-substituted polybenzimidazole (POSS-g-PBI) bearing polyhedral oligomeric silsesquioxane (POSS) pendant moieties were synthesized. X-ray powder diffraction analyses and Scanning electron microscope characterization revealed that POSS was dispersed well in the polybenzimidazole matrix. The grafted POSS pendant moieties can break the PBI intermolecular face-to-face packing and hydrogen bonding. As a result, POSS-g-PBIs showed better solubility than the pure polybenzimidazole because of less tight molecular chain packings. The intrinsic viscosity of POSS-g-PBI in a DMSO solution decreased with increasing amounts of grafted POSS in the polybenzimidazole molecular chains. The mechanical properties, including Young’s modulus, breaking strength and elongation at break, increased by introducing POSS into the polybenzimidazole backbone. Contact angle tests showed that the surface of POSS-g-PBI became hydrophobic with increasing amounts of grafted POSS. POSS-g-PBIs also exhibited good thermal stability.Download high-res image (183KB)Download full-size image

•A colorimetric and fluorescent dual molecular chemosensor was prepared.•The chemosensor can be used as a dual probe for selectively detecting Al3+ and Cu2+.•The limits of detection of Al3+ and Cu2+ were estimated to be 8.3 nM and 2.9 × 10−7 M, respectively.A new rhodamine B derivative bearing a hydrazone group has been designed and prepared. The synthesized colorimetric and fluorescent molecular chemosensor can be used as a dual probe, selectively detecting Al3+ and Cu2+ in acetonitrile solution by monitoring changes in the absorption and fluorescence spectral patterns. The results show that Al3+ ions can induce a greater fluorescence enhancement, while the addition of Cu2+ ions induces a strong UV–vis absorption enhancement with weak fluorescence. The limits of detection of Cu2+ and Al3+ were estimated to be 2.9 × 10−7 M and 8.3 × 10−9 M, respectively.

A novel N-(3-aminopropyl)-imidazole-appended rhodamine-based fluorescent chemosensor was synthesized. The sensing behavior and selectivity of the synthesized chemosensor toward metal cations were studied by UV/vis and fluorescence spectroscopy. The chemosensor recognized Al3+ ions by a significantly enhanced fluorescence and a visible color change due to opening of the spirolactam ring triggered by the addition of Al3+ ions.

Synthesis, structural characterization and property studies were carried out on cubic octa-n-propylsilsesquioxanes (n-Pr-POSS) in this paper. n-Pr-POSS was synthesized by an acid-catalyzed hydrolytic condensation of n-propyltriethoxysilane with a 68.9% yield. Common organic solvents, such as benzene, chloroform, tetrahydrofuran, diethyl ether, dichloromethane, toluene, cyclohexane, hexane and pentane can be used to dissolve n-Pr-POSS; however, n-Pr-POSS is insoluble or poorly soluble in acetone, dichloroethane, chlorobenzene, dimethylformamide, xylene, methanol, alcohol and isopropanol. The cubic structure and crystal morphology of n-Pr-POSS have been investigated by Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), optical microscope, 1H, 13C and 29Si nuclear magnetic resonance (NMR), X-ray single crystal diffraction and X-ray powder diffraction (XRD) methods. Crystalline n-Pr-POSS is a triclinic system crystal with a P-1 space group. Thermogravimetric analysis (TGA) indicates that n-Pr-POSS begins to sublimate above 200 °C and does not decompose until 524 °C under a nitrogen atmosphere.Highlights► Cubic octa-n-propylsilsesquioxanes was synthesized with a 68.9% yield. ► Soluble in common organic solvents. ► A triclinic system crystal with a P-1 space group. ► Sublimate above 200 °C and not to decompose until 524 °C under a nitrogen atmosphere.

Bowl-shaped particles in sub-micrometer scale represent an interesting platform for many potential applications. However, controlled fabrication of this special structure based on polymers still remains a big challenge. In the present study, a controllable sol–gel polymerization procedure was developed to precisely prepare bowl-shaped polysilsesquioxane particles. The morphology of particles can be fine-tuned by judiciously adjusting the amount of two organoalkoxysilane precursors. We explored the formation mechanism of bowl-shaped polysilsesquioxane particles with a kippah structure. The flexibility of the shell and osmotic pressure in combination with centrifugal force should be the key factors to the formation of a bowl-shaped structure.

Ordered dichloro-biphenylene-bridged silsesquioxanes are fabricated by interfacial polymerization at the aqueous/organic phase interface, which involves hydrogen bonding and aromatic π–π stacking interaction, which are responsible for the preferential orientation of the organic bridged units. The high-resolution transmission electronic microscopy images and wide angle X-ray powder diffraction patterns reveal the well-ordered features with lamellar spacings in the hybrid silsesquioxanes. Fluorescence spectra and molecular simulation verify the possibility of ordered structure formation. A general model is developed for the formation of ordered 3,3′-dichloro-biphenylene-bridged silsesquioxanes by interfacial polymerization. This method should offer a convenient avenue for the preparation of highly ordered hybrid network materials.

This report shows an improved selective extraction of the 3,3′-dichlorobenzidine pollutant using molecularly imprinted polysiloxane microspheres (MIPS). 3,3′-Dichlorobenzidine and degradation products are of environmental concern due to their carcinogenic nature. Environmental samples containing 3,3′-dichlorobenzidine are very complex, and the concentration of 3,3′-dichlorobenzidine is usually very low. Current analysis of 3,3′-dichlorobenzidine in environmental matrices often requires cleanup and preconcentration steps that are complex and time-consuming. Therefore, we designed an improved analytical technique. MIPS were synthesized by covalent imprinting. MIPS were characterized by Fourier-transform infrared spectroscopy, nuclear magnetic resonance and transmission electron microscopy. MIPS size ranges from 150 to 250 nm. Adsorption capacity and recognition selectivity toward 3,3′-dichlorobenzidine were studied using ultraviolet spectroscopy and high-performance liquid chromatography. Compared with non-imprinted polysiloxane microspheres, results show that the amount of 3,3′-dichlorobenzidine adsorbed by MIPS is greater by a factor of ten. The binding capacity of MIPS for 3,3′-dichlorobenzidine is seven times larger than diphenylamine. MIPS exhibits high affinity to 3,3′-dichlorobenzidine and can be used for the selective extraction of 3,3′-dichlorobenzidine.

Well architectured polyurethanes containing fluorine are expected to be applied in medical devices as well as other fields. A telechelic polyurethane end-capped with perfluoropolyether segments was prepared from polyether glycol as a soft segment, 4, 4′-methylene-bis-(phenylisocyanate), and monofunctional perfluorinated oligomer. The telechelic polyurethane was studied by Fourier transform infrared spectroscopy (FTIR), gel permeation chromatography (GPC), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), contact angle and atomic force microscopy (AFM). XPS results indicated that the surface of the fluorine containing polyurethane was enriched with fluorine component. It exhibited a hydrophobic property with a water contact angle of 113°. The polyurethane terminated with perfluoropolyether segments showed a better thermal stability. A mechanism was proposed to explain thermal decomposition of polyurethanes. DSC results suggested that the tail-like perfluoropolyether segments would disrupt main chain packing, then raise crystallization potential barrier, and the perfluoropolyether segments did not affect the bulk microphase-separated structure.

Surface geometrical microstructure and low surface free energy are the two most important factors for a self-cleaning surface. In this study, multiform geometrical microstructured surfaces were fabricated by casting and electrospinning polyurethanes with and without low surface energy segments. The effect of low surface energy on water repellency was evaluated. Low surface energy seems to make a more significant contribution to the static wetting behavior than do dynamic properties such as the improvement of sliding behavior. Sucking disk behavior was brought forward to explain the pinning state of a water droplet on hydrophobic surfaces with high water contact angles (>150°). A better understanding of the relationship between the static contact angle and the dynamic sliding property was provided.

Thermal behaviour of polysiloxanes containing cyanoethyl side groups was studied by differential scanning calorimetry (DSC). Samples were quenched to −165 °C and then reheated at different heating rates. The glass transition, an exothermal crystalline formation (cold crystallization) and endothermal melting of crystalline formations were detected. A broad cold crystallization peak and a melting peak were observed at a heating rate of 20 K/min. However, the samples gave a sharp cold crystallization peak and three endothermal peaks using a heating rate of 5 K/min. The DSC traces obtained were thus sensitive to heating rates. Thermal degradation of silazane polymers was studied by a thermogravimetric method. Three stages of degradation occur in the course of thermal decomposition. It was shown that the yields of pyrolytic product increased with the heating rate decreasing.