Abid Muhammad Amin

Hollow Ferrocenyl Coordination Polymer Microspheres with Micropores in Shells Prepared by Ostwald Ripening

Hollow microspheres with pores in their shells have received much attention owing to their hierarchically porous structures and advanced applications in electrochemical capacitive energy storage, hydrogen storage, drug delivery, sensing, and catalysis. For example, Lou et al. reported that hollow SnO2 nanospheres with nanoporous shells showed high reversible charge capacity and good cycling performance. Zhu et al. investigated the drug-delivery properties of hollow silica spheres with mesoporous shells and found that the hollow microspheres were able to store significantly more molecules with higher release rates than conventional mesoporous silica. Template synthesis is one of the most-used strategies to prepare hierarchically hollow microspheres, especially for pores inside the shells. Braun and co-workers have prepared hollow ZnS microspheres with mesoporous shells using dual templates assembled by lyotropic liquid crystals on the surfaces of silica or polystyrene colloidal templates. Liu et al. have produced organic–inorganic hybrid hollow nanospheres with microwindows on the shells templated by tricopolymer aggregates. The template method is general to prepare hollow microspheres with pores in the shells, but expensive and tedious post-treatment processes, such as solvent extraction, thermal pyrolysis, or chemical etching, and resultant fragile frameworks, limit or even impair its applicability. 3, 4] As a result, it remains an important challenge to develop a convenient and template-free method to prepare hollow microspheres with porous shells. Porous coordination polymers are highly ordered porous multifunctional materials prepared by linking metal ions or metal oxide clusters with multidentate organic ligands without any additional template. Construction of shells of hollow materials with porous coordination polymers is an especially promising approach to design hollow microspheres with porous shells through a template-free method and to endow materials with multifunctionality, such as electric, magnetic, and optical properties. Herein, we report the formation of hollow coordination polymer microspheres with microporous shells by a one-pot solvothermal reaction without any additional template; the shells are constructed of iron-based ferrocenyl coordination polymers. We confirm that the Ostwald ripening mechanism is responsible for the formation of hollow cavities with controllable size. Hollow iron-based ferrocenyl coordination polymer microspheres (Fe-Fc-HCPS) were synthesized by a solvothermal reaction of FeCl3·6H2O with 1,1’-ferrocenedicarboxylic acid (H2FcDC) in N,N-dimethyl formamide (DMF; Figure 1a). The precipitate was collected by centrifugation and washed several times with DMF and CHCl3. The reaction temperature, reaction time, and molar ratio of reactants play important roles in the formation of hollow spherical particles. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and optical microscopy (OPM) were

Recent Research Progress in the Synthesis of Polyphosphazene and Their Applications

In the past five decades, many new types of polymers, containing nitrogen and phosphorus atoms as a significant part of the polymer backbone, have been synthesized. This paper reviews the developments in the field of polyphosphazenes and their applications. In this paper, synthesis, characterization, functionalization and practical applications of polyphosphazenes are described.

Study on Poly(ferrocenylsilane) and Its Promotive Effect to Decomposition of Ammonium Perchlorate

S OLID propellant is one of the most significant ingredients used in rockets. The burning rate of propellant is a vital parameter for rocket design. A promising method to enhance the burning rate of propellants is to use burning-rate promoters (BRPs). BRPs have become increasingly important and are receiving more attention recently due to their successful use in solid propellant burning-rate enhancement. Generally, there are several kinds ofBRPs; transitionmetal oxides, nanometal particles, metal chelate, ferrocene, and its derivatives. Transition metal oxide BRPs are cheap, but the burning-rate improvement of propellant is limited. The addition of nanometal particles can enhance the burning rate because nanometal particles have large specific surface areas and higher surface energy. However, nanometal particles are difficult to disperse well and passivation is needed for their surface to prevent spontaneous combustion in air [1]. Organic metal chelate BRPs, such as copper organic chelate and Plumbum iron double metal chelate, can greatly enhance the burning rate due to their good dispersion in propellants. Ferrocene and its derivatives have attracted much attention for their fascinating properties as BRPs [2]. They have been widely used in composite propellant, especially to enhance the burning rate of butyl hydroxide propellant, which contains ammonium perchlorate (AP) and aluminum powder. When ferrocene and its derivatives are used as BRPs, they are easy to migrate during storage. This migration affects their application in propellants. In this Note, we explore the possibility of using a series of poly(ferrocenylsilanes) with highmolecular weights as BRPs.

Recent Research Progress in the Synthesis of Polyphosphazene Elastomers and Their Applications

Polyphosphazenes elastomers have major utilization as fire resistant materials, gas kits, O-rings, electrical insulation, oil-resistant hoses, foam, ceramics, especially helicopter, air craft, aerospace, military and navy hardware applications. Tremendous achievements have been obtained for the synthesis and applications of polyphosphazenes. In this review, we highlighted the types, synthesis, characterization and applications of polyphosphazenes elastomers.

Synthesis and Properties of a Ferrocene-based Metallomesogenic Polymer Containing Bis(4-hydroxyoctoxyphenyl)sulfone

Poly[bis(4-hydroxyoctoxyphenyl)sulfone 1,1′-ferrocene dicarboxylate] (PHOSFD) was synthesized by solution polycondensation reaction of bis(4-hydroxyoctoxyphenyl)sulfone with 1,1′-ferrocenyl chloride. The synthesized polymer was characterized via the measurement of its 1H NMR spectrum, UV–Vis spectrum and FTIR spectrum. X-ray diffraction pattern was measured to investigate the crystallinity of the synthesized polymer and it was found that the polymer is mostly amorphous. The molecular weight of the polymer was determined by gel permeation chromatography. In addition, the electrochemical, the thermal, and the liquid crystalline properties of the synthesized polymer were examined and compared with the properties of poly(diethyleneglycol 1,1′-ferrocene dicarboxylate) (PDEFD) that was synthesized in our earlier study. The electrochemical processes of PHOSFD in CH2Cl2 were confirmed neither to be totally reversible nor completely irreversible. Generally, the electrochemical properties of PHOSFD and PDEFD were found to be similar to each other. PHOSFD was found to be thermally stable but its thermal stability is lower than that of PDEFD. Both of PHOSFD and PDEFD showed liquid crystalline properties and they possessed nematic phase textures with schlieren disclinations during heating and cooling.

Study on the electrochemical, thermal, and liquid crystalline properties of poly(diethyleneglycol 1,1′-ferrocene dicarboxylate)

Poly(diethyleneglycol 1,1′-ferrocene dicarboxylate) (PDEFD) was synthesized by solution polycondensation reaction of diethylene glycol with 1,1′-ferrocenyl chloride. The synthesized polymer was characterized via the measurement of its 1H NMR spectrum, UV–vis spectrum, and FTIR spectrum. X-ray diffraction pattern was measured to investigate the crystallinity of the synthesized polymer and it was found that the polymer was mostly amorphous. The molecular weight of the polymer was determined by gel permeation chromatography. In addition, the electrochemical properties of the synthesized polymer were examined and the influence of many parameters, including the solvent, the scan rate, and the electrolyte concentration was studied. The electrode processes were found to be controlled by both electrode reaction and the mass diffusion. In addition, the electrochemical processes of PDEFD in dimethyl sulfoxide (DMSO) were confirmed neither to be totally reversible nor completely irreversible. Moreover, the thermogravimetric analysis and differential thermal analysis were employed to examine the thermal properties of the polymer. Finally, the liquid crystalline properties of the synthesized polymer were investigated via the polarizing optical microscope technique.

Synthesis and Characterization of Poly(bis(ethyl salicylate)phosphazenes) and Poly(bis(ethyl salicylate diethylamino)phosphazenes) and Their Hydrolytic Degradation

The polydichlorophosphazenes were synthesized from hexachlorocyclotriphosphazenes by ring opening polymerization in the presence of AlCl3 as a catalyst. Poly[bis(ethyl salicylate)phosphazenes] (PESP) and poly[bis(ethyl salicylate diethylamino)phosphazenes] (PESDEAP) were synthesized via macromolecular substitution reactions using ethyl salicylate and (or) diethylamine as side groups. The synthesis results were proved by nuclear magnetic resonance (1H NMR, and 31P NMR) and gel permeation chromatography. In addition, the hydrolytic degradation of PESP and PESDEAP was investigated at constant temperature in neutral medium.

Synthesis and Characterization of Poly[bis(p-oxybenzaldehyde diethylamino)phosphazenes], Poly[bis(p-oxybenzaldehyde)phosphazenes], Poly[bis(diethylamino)phosphazenes] and their Self- assembly Behaviors

Polydichlorophosphazenes (PDCP) were synthesized through ring opening polymerization of hexachlorocyclotriphosphazene (HCCP). The polymerization behavior of HCCP under varying conditions of time and amount of catalyst was investigated. The chlorine atoms in polydichlorophosphazenes (PDCP) were substituted with p-oxybenzaldehyde and (or) diethylamine to synthesize poly[bis(p-oxybenzaldehyde diethylamino)phosphazenes](PPOBADEAP), poly[bis(p-oxybenzaldehyde)phosphazenes] (PPOBAP) and poly[bis(diethyl amino) phosphazenes] (PDEAP). The supporting evidence for the success of this synthesis was provided by nuclear magnetic resonance (1H-NMR, and 31P-NMR), gel permeation chromatography (GPC), and energy-dispersive X-ray spectroscopy (EDAX). The self-assembly behavior of PPOBADEAP, PPOBAP and PDEAP was observed in different solvents by the same concentration of polymers. The optical microscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images indicated that PPOBADEAP formed various morphologies in different solvents while PPOBAP and PDEAP did not show self-assembly behavior at the same conditions.