Wangchang Geng

Effect of large pore size of multifunctional mesoporous microsphere on removal of heavy metal ions.

Pore size of mesoporous materials is crucial for their surface grafting. This article develops a novel multifunctional microsphere with a large pore size mesoporous silica shell (ca. 10.3 nm) and a magnetic core (Fe₃O₄), which is fabricated using cetyltrimethylammonium bromide (CTAB) as pore-forming agents, tetraethyl orthosilicate (TEOS) as silicon source through a sol-gel process. Compared with small pore size mesoporous silica magnetic microspheres (ca. 2-4 nm), the large pore size one can graft 447 mg/g amino groups in order to adsorb more heavy metal ions (Pb(2+): 880.6 mg/g, Cu(2+): 628.3mg/g, Cd(2+): 492.4 mg/g). The metal-loaded multifunctional microspheres could be easily removed from aqueous solution by magnetic separation and regenerated easily by acid treatment. The results suggest that the large pore size multifunctional microspheres are potentially useful materials for high effectively adsorbing and removing different heavy metal ions in aqueous solution.

Thermal conductivities, mechanical and thermal properties of graphite nanoplatelets/polyphenylene sulfide composites

Functionalized pristine graphite nanoplatelets (fGNPs) by methanesulfonic acid/isopropyltrioleictitanate (MSA/NDZ-105) are used to fabricate fGNPs/polyphenylene sulfide (fGNPs/PPS) composites by mechanical ball milling followed by a compression molding method. The thermal conductive coefficient of the fGNPs/PPS composite with 40 wt% fGNPs is greatly improved to 4.414 W m−1 K−1, 19 times higher than that of the original PPS. For a given GNP loading, the surface functionalization of GNPs by MSA/NDZ-105 results in the fGNPs/PPS composites improving thermal conductivities by minimizing the interfacial thermal resistance. The thermal stabilities of the fGNPs/PPS composites are increased with the increasing addition of fGNPs.

Comprehensive study of mesoporous carbon functionalized with carboxylate groups and magnetic nanoparticles as a promising adsorbent

Highly ordered mesoporous carbon functionalized with carboxylate groups and magnetic nanoparticles has been successfully synthesized. By oxidative treatment using (NH(4))(2)S(2)O(8) and H(2)SO(4) mixed solution, numerous hydrophilic groups were created in the mesopores without destroying the ordered mesostructure of CMK-3. Through the in situ reduction in Fe(3+), magnetic nanoparticles were successfully introduced into the mesopores, resulting in the multifunctional mesoporous carbon Fe-CMK-3. The obtained hybrid carbon material possesses ordered mesostructure, high Brunauer-Emmett-Teller (BET) surface area up to 1013 m(2)/g, large pore volume of about 1.16 cm(3)/g, carboxylic surface, and excellent magnetic property. When used as an adsorbent, Fe-CMK-3 exhibits excellent performances for removing toxic organic compounds from waster-water, with a high adsorption capacity, an extremely rapid adsorption rate, and an easy magnetically separable process. In the case of requiring emergency removal of large amount of organic pollutants in aqueous, the hybrid carbon adsorbent would be an ideal choice.

Fabrication of one-dimensional Fe3O4/P(GMA-DVB) nanochains by magnetic-field-induced precipitation polymerization.

One-dimensional (1D) magnetic Fe(3)O(4)/P(GMA-DVB) peapod-like nanochains have been successfully synthesized by magnetic-field-induced precipitation polymerization using Fe(3)O(4) as building blocks and P(GMA-DVB) as linker. The Fe(3)O(4) microspheres without surface modification can be arranged with the direction of the external magnetic field in a line via the dipolar interaction between Fe(3)O(4) microspheres and linked permanently via P(GMA-DVB) coating during precipitation polymerization. The length of peapod-like nanochains can be controlled by magnetic field intensity, and the thickness of polymer shell can be tuned by the amount of monomers. Magnetic measurement revealed that these 1D peapod-like nanochains showed highly magnetic sensitivity. In the presence of magnetic field, 1D magnetic Fe(3)O(4)/P(GMA-DVB) peapod-like nanochains can be oriented and aligned along the direction of external magnetic field.

Surface modification of HMPBO fibers by silane coupling agent of KH-560 treatment assisted by ultrasonic vibration

The surface modification of poly (p-phenylene-2,6-benzobisoxazole) (HMPBO) fibers by silane coupling agent of γ-aminopropyl triethoxy silane (KH-560) treatment assisted by ultrasonic vibration was investigated. The chemical composition and surface morphologies of the HMPBO fibers were analyzed and characterized by XPS, FTIR, TGA and SEM. The tensile properties of the HMPBO fibers were also studied. The results indicated that polar hydroxyl groups were successfully introduced on the HMPBO surface after the proposed treatment processes, and the surface roughness of HMPBO fibers was increased. Moreover, the treated HMPBO maintained relatively excellent tensile strength, and the single fiber pull-out strength of HMPBO was improved from 0.94 MPa to 1.07 MPa.

Synthesis of poly (methyl methacrylate)-b-polystyrene with high molecular weight by DPE seeded emulsion polymerization and its application in proton exchange membrane.

In this article, we present poly (methyl methacrylate)-b-polystyrene (PMMA-b-PS) with different block ratios and high molecular weight, which was synthesized by environmentally friendly seeded emulsion polymerization with 1,1-diphenylethylene (DPE) as a chain transfer agent. Polymerization kinetics in the first and second stage was investigated. Stable latex and homogeneous latex particles were obtained with the characterization of laser light scattering (LLS) and transmission electron microscopy (TEM). SEC and (1)H NMR revealed the successful preparation of block copolymers with high molecular weight and two different block ratios. The morphology of microphase separation of block copolymer thin films was investigated by AFM, and long-range order lamellar morphology was observed after vapor-annealing. The block copolymer with block ratio of almost 1:1 and higher molecular weight than that of previous PMMA-b-PS was sulfonated with acetyl sulfate, and the sulfonation was confirmed by FTIR, (1)H NMR, and TGA. Then, the sulfonated PMMA-b-PS was casted as membranes. The electrochemical impedance spectroscopy displayed that membranes possessed favorable proton conductivity and fine dimensional stability, and they could be candidates as proton exchange membranes.

Synthesis of rattle-type magnetic mesoporous Fe3O4@mSiO2@BiOBr hierarchical photocatalyst and investigation of its photoactivity in the degradation of methylene blue

A rattle-type magnetic mesoporous Fe3O4@mSiO2@BiOBr hierarchical photocatalyst was successfully synthesized by a facile solvothermal method under the orientation of the surface amino-groups of rattle-type magnetic mesoporous Fe3O4@mSiO2 microspheres. Then, this photocatalyst was characterized via X-ray diffraction, transmission electron microscopy, field-emitting scanning electron microscopy, Fourier transform-infrared spectroscopy, X-ray photoelectron spectroscopy and vibrating sample magnetometry. Due to the presence of an inner cavity and orderly mesoporous opening structure, this novel photocatalyst exhibits superior adsorption and transfer performance to organic contaminants in aqueous systems. In particular, the complex between BiOBr and SiO2 had significantly increased absorption ability to visible-light due to the some extent of the direct contact of the interfaces of the two materials. Studies show that the assembly capacity of BiOBr nanosheets plays an important role in enhancing the photoactivity. Even though methylene blue is a relatively stable organic contaminant, it can still be decomposed completely by this novel photocatalyst in a very short amount of time (about 120 min). Encouragingly, the photoactivity of this novel photocatalyst is far higher (about 2.6 times) than that of pure BiOBr photocatalyst for its unique structure. According to the radical trapping experiments, the photogenerated holes (h+) and superoxide radicals (O2˙−) are considered to be the main active species that drive the photodegradation under visible-light irradiation. Due to the unique structures and fast interfacial charge transfer, this novel photocatalyst is absolutely a superior alternative visible-light-driven photocatalyst.

Microencapsulation of hexadecane by surface-initiated atom transfer radical polymerization on a Pickering stabilizer

Hexadecane-loaded microcapsules with SiO2–poly(methyl methacrylate) (PMMA) hybrids as shells were prepared by surface-initiated atom transfer radical polymerization (SI-ATRP) in an oil-in-water Pickering emulsion. ATRP-initiators were introduced onto SiO2 particles by a homemade silane coupling reagent containing a 2-bromoisobutyrate group. SI-ATRP polymerization was conducted on Pickering stabilizers based on activators regenerated by electron transfer (ARGET). TGA results indicated that 80.3% of PMMA chains in the shell were covalently-bonded to SiO2, which was formed by SI-ATRP polymerization. The microcapsules show excellent potential for thermal energy storage, as evidenced by a high melting enthalpy of 161.7 J g−1.

Fabrication of 1D Fe3O4/P(NIPAM-MBA) thermosensitive nanochains by magnetic-field-induced precipitation polymerization

One-dimensional (ID) magnetic thermosensitive Fe3O4/poly(N-isopropylacrylamide–N,N′-methylenebisacrylamide) (P(NIPAM-MBA)) peapod-like nanochains have been successfully synthesized by magnetic-field-induced precipitation polymerization using Fe3O4 as building blocks and P(NIPAM-MBA) as linker. Fe3O4 microspheres can be arranged with the direction of an external magnetic field in a line via the dipolar interaction between Fe3O4 microspheres and linked permanently via P(NIPAM-MBA) coating during precipitation polymerization. 1D magnetic Fe3O4/P(NIPAM-MBA) peapod-like nanochains can be oriented and aligned along the direction of the external magnetic field. More interestingly, Fe3O4 microspheres in each peapod were regularly arranged in a line and periodically separated through the P(NIPAM-MBA) layers with a visible interparticle spacing.

Ultrahigh humidity sensitivity of NaCl-added 3D mesoporous silica KIT-6 and its sensing mechanism

Mesoporous silica KIT-6 was synthesized by a hydrothermal method and NaCl-added KIT-6 was prepared by a facile grind method. Compared with pure KIT-6, NaCl-added KIT-6 showed greatly improved humidity sensitivity. The impedance changed by more than five orders of magnitude over the whole humidity range (11–95% RH). The response time was about 47 s. Complex impedance spectra were also provided and discussed in detail to explore the humidity sensing mechanism of NaCl-added KIT-6.