Effect of cetyltrimethylammonium bromide on morphology and porous structure of mesoporous hydroxyapatite

The mesoporous hydroxyapatite （HA） was synthesized by hydrothermal method utilizing cationic surfactant cetyltrimethylammonium bromide （CTAB） as template. The crystalline phase, morphology and porous structure were characterized respectively by different detecting techniques. The results reveal that the particles are highly crystalline hydroxyapatite phase. The surfactant has little influence on the morphology of the crystals, but affects the porous structure obviously. The sample without CTAB has a low surface area not exceeding 33 m^2/g, and no distinct pores can be observed by TEM. While the samples obtained with the surfactant get better parameters. Numerous open-ended pores centered at 2-7 nm spread unequally on the surface of the hydroxyapatite nanorods. The N2 adsorption-desorption experiments show type IV isotherms with distinct hysteresis loops, illustrating the presence of mesoporous structure. When the mole ratio of CTAB to HA is 1：2, the sample has the largest surface area of 97.1 m^2/g and pore volume of 0.466 cm^3/g.

Interconnected MXene/Graphene Network Constructed by Soft Template for Multi‑Performance Improvement of Polymer Composites

The multi-functionalization of polymer composites refers to the ability to connect multiple properties through simple structural design and simultaneously achieve multi-performance optimization.The large-scale design and mass production to realize the reasonable structure design of multifunctional polymer composites are urgently remaining challenges.Herein,the multifunctional MXene/graphene/polymer composites with three-dimensional thermally and electrically conductive network structures are fabricated via the utilization of the microstructure of the soft template,and a facile dispersion dip-coating approach.As a result,the polymer composites have a multiperformance improvement.At the MXene and graphene content of 18.7 wt%,the superior throughplane thermal conductivity of polymer composite is 2.44 W m^(−1)K^(−1),which is 1118%higher than that of the polymer matrix.The electromagnetic interference(EMI)shielding effectiveness of the sample reaches 43.3 dB in the range of X-band.And the mechanical property of the sample has advanced 4 times compared with the polymer matrix.The excellent EMI shielding and thermal management performance,along with the effortless and easy-to-scalable producing techniques,imply promising perspectives of the polymer composites in the next-generation smart electronic devices.

Polypyrrole Micro/Nanostructure Prepared Using Azo Dyes with Different Substituents

This contribution deals with simple way of polypyrrole structure modification. Using azo dyes in polymerization reaction as soft-template with similar molecular structure but different type and distribution of substitution groups lead to formation of one-dimensional and newly also three-dimensional polypyrrole micro/nanostructures. These structures are characteristic with geometrical symmetry and uniformity. Geometry of prepared structures was studied by scanning electron microscopy (SEM) and by methods of image analysis;nanotubes are hundreds of nm in diameter and units of μm in length, new tree-dimensional structures have units of μm in diameter. Infrared spectra (ATR-FTIR) confirmed that azo dyes work only as intermediate supporting structures without reaction with polypyrrole.

Size-dependent activity of Fe-N-doped mesoporous carbon nanoparticles towards oxygen reduction reaction

The rational design of Fe–N–C catalysts that possess easily accessible active sites and favorable mass transfer,which are usually determined by the structure of catalyst supports,is crucial for the oxygen reduction reaction(ORR).In this study,an oleic acid-assisted soft-templating approach is developed to synthesize size-controlled nitrogen-doped carbon nanoparticles(ranging from 130 nm to 60 nm and 35 nm,respectively)that feature spiral mesopores on their surface(SMCs).Next,atomically dispersed Fe–Nx sites are fabricated on the size-tunable SMCs(Fe1/SMC-x,where x represents the SMC size)and the size-dependent activity toward ORR is investigated.It is found that the catalytic performance of Fe1/SMCs is significantly influenced by the size of SMCs,where the Fe1/SMC-60 catalyst shows the highest ORR activity with a half-wave potential of 0.90 V vs.RHE in KOH electrolyte,indicating that the gas-liquid-solid three-phase interface on the Fe1/SMC-60 enhances the accessibility of Fe–Nx sites.In addition,when using Fe1/SMC-60 as the cathode catalyst in aqueous zinc-air batteries(ZABs),it delivers a higher open-circuit voltage(1.514 V),a greater power density(223 mW cm^(−2)),and a larger specific capacity/energy than Pt/C-based counterparts.These results further highlight the potential of Fe1/SMC60 for practical energy devices associated with ORR and the importance of size-controlled synthesis of SMCs.

Controlled growth of ZnO nanorods by polymer template and their photoluminescence properties

A large amount of one-dimensional ZnO nanorods with diameters in 15―50 nm aligned in radial cluster were successfully synthesized by polar polymer polyvinyl alcohol (PVA) as soft-template. The growth of ZnO nanorods was controlled by changing annealing temperature. The evolution of the morphology and microstructure was investigated by scanning electron microscope, transmission electron micro- scope and X-ray diffraction. It is shown that ZnO nanorods tend to be uniform and the crystallization is gradually improved with the temperature increasing from 400℃ to 700℃. The photoluminescence spectra of products show a strong ultra violet emission and relatively weak defect emissions. The sharp strong emission peak at 354 nm owing to the inter-band transition indicates the extraordinary photoluminescence property of ZnO nanorods.

Sol-gel synthesis,properties and protein loading/delivery capacity of hollow bioactive glass nanospheres with large hollow cavity and mesoporous shell

Hollow nanospheres exhibit unique properties and find a wide interest in several potential applications such as drug delivery.Herein,novel hollow bioactive glass nanospheres(HBGn)with large hollow cavity and large mesopores in their outer shells were synthesized by a simple and facile one-pot ultrasound assisted sol-gel method using PEG as the core soft-template.Interestingly,the produced HBGn exhibited large hollow cavity with ~43 nm in diameter and mesoporous shell of ~37 nm in thickness and 7 nm pore size along with nanosphere size around 117 nm.XPS confirmed the presence of Si and Ca elements at the surface of the HBGn outer shell.Notably,HBGn showed high protein loading capacity(~570 mg of Cyto c per 1 g of HBGn)in addition to controlled protein release over 5 d.HBGn also demonstrated a good in vitro capability of releasing calcium(Ca^(2+):170 ppm)and silicate(SiO_(4)^(4-):78 ppm)ions in an aqueous medium over 2 weeks under physiological-like conditions.Excellent in vitro growth of bone-like hydroxyapatite nanocrystals was exhibited by HBGn during the soaking in SBF.A possible underlying mechanism involving the formation of spherical aggregates(coils)of PEG was proposed for the formation process of HBGn.