Incorporation of dye into conducting polyaniline nanoparticles

Synthesis of polyaniline (PANi) nanodispersions with and without the presence of a reactive dye has been performed via micellar chemical oxidative polymerisation using dodecylbenzene sulfonic acid (DBSA) as the dispersant. The dye used was a textile reactive dye (Carbolan Blue – CB) which was chosen due to it’s structural similarity to DBSA. The polymers formed were PANi · DBSA and PANi · DBSA · CB. The inclusion of the CB dye appeared to facilitate the polymerisation process as observed from open circuit potential measurements during polymerisation. Using transmission electron microscopy, PANi · DBSA · CB was shown to have an average particle size larger than that observed for PANi · DBSA. The CB dye was shown to be incorporated into the polymer by Raman spectroscopy. The CB containing polymer was amenable to protonation/deprotonation as well as redox switching.     

Sulfonic acid catalyst based on silica foam supported copolymer for hydrolysis of cellulose

Mesocellular silicon foam supported poly(chloromethylstyrene-co-divinylbenzene) (MCF–copolymer) was synthesized. It has a pore size of 24.2 nm. The pore volume and the surface area were 0.84 cm³/g and 246.9 m²/g, respectively. MCF–copolymer supported sulfonic acid was accomplished via sulfonation with concentrated sulfuric acid. The acid amount on the MCF–copolymer was 2.03 mmol/g. Hydrolysis of banana pseudo-stem fibers and microcrystalline cellulose was carried out over the catalyst. The large pore size favors the diffusion of molecules in catalyzing bulky molecules. The corresponding catalytic turnover frequencies (TOF) were 5.57 h^− 1 and 8.066 h^− 1.     

White-light-emitting diodes from single polymer systems based on polyfluorene copolymers end-capped with a dye

New polymer white-light-emitting diodes from single polymer systems have been developed. The polymer systems were based on poly(fluorene-co-benzothiadiazole) backbones end-capped with a green-emission dye, N-phenyl-1,8-naphthalimide. By changing the molar ratio of these three units, the electroluminescence (EL) spectra can be adjusted to white-light emission with a structure of indium tin oxide/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonic acid)/emission layer/Ca/Ag. The highest brightness in such a device configuration is 251 cd/m² at a current density of 400 A/m² with Commission Internationale de l'Eclairage (CIE) coordinates of (0.31,0.39). The EL spectra show color stability over different operating voltages.     

Microstructure and properties of diamond/SiC composites prepared by tape-casting and chemical vapor infiltration process

This article reported a novel method for preparing diamond/SiC composites by tape-casting and chemical vapor infiltration (CVI) process, and the advantages of this method were discussed. The diamond particle was proved to be thermally stable under CVI conditions and the CVI diamond/SiC composites only contained diamond and CVI-SiC phases. The SEM and TEM results showed a strong interfacial bonding existed between diamond and CVI-SiC matrix. Due to the strong bonding, the surface HRA hardness could reach up to 98.4 (HV 50 ± 5 GPa) and the thermal conductivity (TC) of composites was five times higher than that of pure CVI-SiC matrix. Additionally, the effects of diamond particle size on microstructure and properties of composites were also investigated. With the increasing of particle size, the density and TC of composites with the size 27 μm reached 2.940 g/cm³ and 82 W/(m K), respectively.     

Epoxidation of pendant allyl groups in poly(ester-anhydride)s proposed for application in drug delivery

This paper describes the synthesis and modification of functional poly(ester-anhydride)s that have potential for a variety of applications in drug delivery. Functional poly(ester-anhydride)s with pendant allyl groups were synthesized by two step polycondensation of oligo(3-allyloxy-1,2-propylene succinate) terminated with carboxyl end groups (OSAGE) and one of diacids (DA): sebacic (SBA) or dodecanedicarboxylic acid (DDC). Poly(ester-anhydride)s with molecular weights with range of 3100–7300 Da and with varying degree of functionality were oxidized with m-chloroperbenzoic acid (MCPBA) to yield respective polymers with epoxy pendant groups. The OSAGE to DA ratio in the poly(ester-anhydride)s, polymer concentration in the reaction solution, excess of MCPBA and duration of the reaction, had influenced the conversion of allyl groups into glycidyl ones. For all types of poly(ester-anhydride)s conditions were set up in which 100% of epoxidation could be achieved. Completely oxidized poly(ester-anhydride)s were characterized by means of ¹H NMR spectroscopy and DSC technique. Their thermal and solubility characteristics were compared with characteristics of initial poly(ester-anhydride)s. Initial and oxidized polymers containing 80% of SBA or DDC were formulated into microspheres using O/W emulsion technique. The presence of epoxy groups at the surface of microspheres were confirmed by ATR IR spectroscopy. Microspheres obtained were subjected to hydrolytic degradation at 37 °C, in aqueous phosphate buffer solution of pH = 7.41 (PBS).     

Powerful adsorption of silver(I) onto thiol-functionalized polysilsesquioxane microspheres

The strong adsorbability of Ag(I) ions onto poly(3-mercaptopropylsilsesquioxane) (PMPSQ) microspheres synthesized through a two-step acid–base catalyzed sol–gel process method was systematically examined. The effect of adsorption time, initial Ag(I) concentration, and solution pH was studied to optimize the Ag(I) adsorbability of PMPSQ microspheres. The PMPSQ microspheres demonstrate a powerful Ag(I) adsorbability with an adsorptivity above 99.99% when the initial Ag(I) concentration is lower than 10 mM and the highest Ag(I) adsorbance of 1140 mg/g at an initial Ag(I) concentration of 150 mM. Adsorption phenomena appeared to follow Langmuir isotherm. The kinetic studies indicated that the adsorption process well fits the pseudo-second-order kinetics with a very rapid initial adsorption rate of 15.28 mg g^?1 min^?1. The appropriate solution pH for Ag(I) adsorption is around 2.0–5.4. The PMPSQ microspheres demonstrate a promising application in the removal of Ag(I) ions from aqueous solutions.     

Methacrylic acid microcellular highly porous monoliths: Preparation and functionalisation

By polymerisation of high internal phase emulsions (HIPEs), containing styrene (STY), divinylbenzene (DVB) and methacrylic acid (MAA) in the continuous phase, highly porous polymers including carboxylic functional groups were prepared. The ratio of methacrylic acid to divinylbenzene was varied in order to obtain polyHIPEs with a different degree of crosslinking which influenced a surface area of the polymers, being substantially higher (185 m²/g) with a higher degree of crosslinking (51% DVB) than with a lower degree of crosslinking (24% DVB, 46 m²/g). Up to 90% porous samples were prepared and the optimum hidrophilicity-lipophilicity balance (HLB) of the surfactant was found to be around 4.8–4.9. Both thermal and photo initiation were used to induce polymerisation. The resulting polymers had an open cellular morphology with cavity diameters between 21.8 μm and 44.2 μm and with interconnecting pores between 2.2 μm and 5.0 μm. Monolithic supports were used for further functionalisation with thionyl chloride and multifunctional amines, namely 1,4-diaminobutane and 1,12-diaminododecane. The functionalisation degree with thionyl chloride was 76%.     

Ceramic microspheres with controlled porosity by emulsion-ice templating

Silicon Carbide porous microspheres were fabricated using a preceramic polymer by emulsion-ice templating. An oil-in-water macroemulsion was prepared by adding an organic solution, comprising polycarbosilane and cyclohexane, to the aqueous phase containing a nonionic surfactant. Upon directional freezing and freeze drying, microspheres with aligned pores were obtained. The influence of processing parameters was assessed. In particular, the solidification temperature affected size and morphology of the macroporosity. Our strategy enables an independent control of macro and nanoporosity. Indeed, the thermal treatment can be optimized to tune the micro-porosity at the nanoscale as well as the specific surface area of the samples.The emulsion-ice templating technique was optimized to produce microspheres with multimodal macroporosity up to 90 vol.% in the range 1–30 μm, with micro- and meso-pores with diameter up to 6 nm, and specific surface area as high as 117 m² g⁻¹.     

The adsorptive extraction of oxidized sulfur-containing compounds from fuels by using molecularly imprinted chitosan materials

An innovative approach for desulfurisation of fuels is proposed. It relies on the formation of recognition sites, complementary to oxidized sulfur-containing compounds, on cross-linked chitosan microspheres and electrospun chitosan nanofibers using the molecularly imprinted polymer technique. Benzothiophene sulfone (BTO₂), dibenzothiophene sulfone (DBTO₂) and 4,6-dimethyldibenzothiophene sulfone (4,6-DMDBTO₂) were used as templates for the preparation of molecularly imprinted polymers (MIPs). The possible molecular interactions between imprinted chitosan adsorbent and oxidized sulfur-containing compounds were investigated by molecular modeling using density functional theory (DFT) and results indicated that interactions took place via hydrogen bonding. The molecularly imprinted polymer adsorbents (cross-linked microspheres and electrospun nanofibers) gave better selectivity for the target sulfonated compounds and the adsorption isothermal studies followed the Freundlich model. Maximum adsorption capacities of 8.5 ± 0.6 mg/g, 7.0 ± 0.5 mg/g and 6.6 ± 0.7 mg/g were observed for model BTO₂, DBTO₂ and 4,6-DMDBTO₂ respectively at 1 mL/h when imprinted nanofibers were employed, and the imprinted microspheres gave maximum adsorption capacity of 4.9 ± 0.5 mg/g, 4.2 ± 0.7 mg/g and 3.9 ± 0.6 mg/g for BTO₂, DBTO₂ and 4,6-DMDBTO₂ respectively. Application of the nanofibers to oxidized hydro-treated fuel under continuous flow adsorption system at 1 mL/h indicated that 84% of sulfur was adsorbed, with adsorption capacity of 2.2 ± 0.2 mg/g.     

Preparation and properties of bimodal porous apatite ceramics through slip casting using different hydroxyapatite powders

A bimodal porous hydroxyapatite (HAp) body with high flexural strength was prepared through slip casting. The effect of different particle sizes on the flexural strength and microstructure of three different types of hydroxyapatite (HAp) powders was studied. The powder characteristic of laboratory-synthesized HAp powder (L-HAp) was obtained through a wet-milling method, drying and heating of a mixture of calcium hydrogen phosphate di-hydrate and calcium carbonate. The median particle size of L-HAp was 0.34 μm, and the specific surface area was 38.01 m²/g. The commercial HAp had median particle sizes for the K-HAp (Kishida chemical Co. Ltd., K-HAp) and T-HAp (Taihei chemical Co. Ltd., T-HAp) of 1.13 and 3.65 μm, and specific surface areas of 11.62 and 6.23 m²/g, respectively. The different powder characteristics affected the slip characteristics, and the flexural strength and microstructure of the sintered porous HAp bodies were also different. The flexural strengths of the porous HAp ceramics prepared by heating at 1200 °C for 3 h in air were 17.59 MPa for L-HAp with a porosity of 60.48%, 3.92 MPa for commercial K-HAp with a porosity of 79.37%, and 4.55 MPa for commercial T-HAp with a porosity of 76.46%.     

Synthesis and characterization of magnetic polyHIPEs with humic acid surface modified magnetic iron oxide nanoparticles

Magnetic macroporous polymer monoliths have been prepared using styrene/divinylbenzene (S/DVB) high internal phase emulsions (HIPEs) as templates. Humic acid surface modified iron oxide magnetic nanoparticles (Fe₃O₄@HA) have been used to prepare magnetic emulsion templates. The effect of magnetic particle concentration has been investigated by changing the ratio of Fe₃O₄@HA nanoparticles in the continuous phase. Highly macroporous polymers with magnetic response were obtained by the removal of the internal phase after the curing of emulsions at 80 °C. Fe₃O₄@HA particles were characterized by XRD and FTIR. The porosity, pore morphology and magnetic properties of the macroporous polymers were characterized as a function of the Fe₃O₄@HA concentration by scanning electron microscopy (SEM), Brunauer–Emmet–Teller (BET) molecular adsorption method and vibrating sample magnetometry (VSM), respectively. BET and VSM measurements demonstrated that the specific surface area and the saturation magnetization of the polymer monoliths were changed according to the Fe₃O₄@HA concentration between 8.77–35.08 m² g^?1 and 0.63–11.79 emu g^?1, respectively. Resulting magnetic monoliths were tested on the adsorption of Hg(II) and atomic absorption spectroscopy (AAS) was used to calculate the adsorption capacities. The maximum adsorption capacity of the magnetic monoliths was calculated to be 20.44 mmol g^?1 at pH 4.     

Zn2+-imprinted porous polymer beads: Synthesis,structure, and selective adsorption behavior for template ion

Zn²⁺-imprinted polymer was synthesized in porous spherical forms via a self-assembled complex between 2,2′-bipyridyl/4-vinylpyridine complexant/functional monomer and Zn²⁺ template ion. Diameters of particles ranged from 250 to 550 μm to enlarge the surface area and thus enhance the adsorption capacity. The presence/absence of the template ion in the preparation of the imprinted polymer was confirmed by EDX spectroscopy, and the physical structure of the particles was investigated using ESEM and BET analysis. The particle and the pore size were controlled by the cross-linker/monomer feed ratio. The adsorption capacity of the imprinted polymers was 210.61 μmol g^?1 for Zn²⁺, while those for Cu²⁺, Ni²⁺, and Pb²⁺, were 37.92 μmol g^?1, 33.02 μmol g^?1, and 9.70 μmol g^?1, respectively. This big discrepancy of the adsorption capacities illustrates the excellent separation selectivity of the imprinted polymers. The adsorption capacity decreased significantly at pH below 4.5, as the polymers are easily protonated. The imprinted particles lost only 10 % of their adsorption ability after 10 repeated uses.     

Processing of microcellular silicon carbide ceramics with a duplex pore structure

A novel processing route for producing microcellular SiC ceramics with a duplex pore structure has been developed using a polysiloxane, carbon black, SiC, Al₂O₃, Y₂O₃, and two kinds of pore former (expandable microspheres and PMMA spheres). The duplex pore structure consists of large pores derived from the expandable microspheres and small windows in the strut area that were replicated from the PMMA spheres. The presence of these small windows in the strut area improved the permeability of the porous ceramics. The gas permeability coefficients of porous SiC ceramics were 0.13 × 10¹² m² for the porous SiC without PMMA spheres, 0.47 × 10¹² m² for the porous SiC with 10 wt% PMMA spheres, and 0.82 × 10¹² m² for the porous SiC with 20 wt% PMMA.     

Effects of carbon surface area on performance of lithium sulfur battery cathodes

The effect of carbon surface area on capacity is investigated in cathodes for lithium sulfur batteries. Carbon additives help overcome the low electrical conductivity of sulfur. Cathodes were prepared at 30 wt% sulfur on different activated carbons having unloaded BET surface areas of 1200–3200 m²/g. Sulfur utilization ranged from 33% to 83% of the theoretical capacity (1672 mAh/g) with a strong correlation to the accessible pore volumes having pore widths between 1 and 5 nm. Additionally, cathodes prepared at 12.5–68 wt% on an activated carbon having unloaded BET surface area of 3200 m²/g showed excessive sulfur loading provided little additional capacity.     

Synthesis,calcination and characterization of Nanosized ceria powders by self-propagating room temperature method

Nanometric ceria powders with fluorite-type structure were obtained by applying self-propagating room temperature method. The obtained powders were subsequently thermally treated (calcined) at different temperatures for different times. Powder properties such as specific surface area, crystallite size, particle size and lattice parameter have been studied. Roentgen diffraction analysis (XRD), BET and Raman scattering measurements were used to characterize the as-obtained (uncalcined) powder as well as powders calcined at different temperatures.It was found that the average diameter of the as-obtained crystallites is in the range of 3–5 nm whereas the specific surface area is about 70 m²/g. The subsequent, 15 min long, calcination of as-obtained powder at different temperatures gradually increased crystallite size up to ～60 nm and reduced specific surface down to 6 m²/g. Raman spectra of synthesized CeO_2?y depicts a strong red shift of active triply degenerate F_2 g mode as well as additional peak at 600 cm^?1. The frequency of F_2 g mode increased while its line width decreased with an increase in calcination temperature. Such a behavior is considered to be the result of particle size increase and agglomeration during the calcination. After the heat treatment at 800 °C crystallite size reached value larger than 50 nm. Second order Raman mode, which originates from intrinsic oxygen vacancies, disappeared after calcination.     

Near critical and supercritical impregnation and kinetic release of thymol in LLDPE films used for food packaging

The impregnation of organic compounds in polymeric materials using supercritical carbon dioxide (scCO₂) is a well-known technique, which is currently used in drug/polymer formulation. In this work, near critical and supercritical impregnation of thymol in linear low-density polyethylene (LLDPE) films was done in order to develop a new technique for preparation of active polymers to be used as food packages. The properties of thymol as a natural antimicrobial and antioxidant agent have motivated this study about the assessment of its migration from the polymer to different food simulant. Impregnation assays of thymol in LLDPE films were done in a high-pressure cell, where pure thymol was solubilized in supercritical carbon dioxide at 313 K and pressures varying from 7 to 12 MPa. This procedure allowed the preparation of plastic films with thymol concentrations ranged between 5100 and 13,200 ppm. Migration tests showed that the pressure applied during the impregnation procedure is a key parameter that affects the content of the active compound into the polymer, since thymol solubility in scCO₂ and absorption phenomena in the polymer increased with the pressure. The correlation between experimental data and a phenomenological transfer model allowed the estimation of the diffusion coefficient of thymol in LLDPE, which was ranged from 7.5 × 10⁻¹³ to 3.0 × 10⁻¹² m² s⁻¹.     

Preparation of amino-functionalized silica for copper removal from an aqueous solution

In the present research, amino-functionalized silica materials were synthesized to develop absorbents for removing copper (II) ions from water. Three kinds of silica with various BET surface areas and pore volumes (331.4 m²/g, 460.1 m²/g, 717.7 m²/g and 1.38 cm³/g, 1.06 cm³/g, 0.57 cm³/g, respectively) were used to determine an optimum material. 3-Aminopropyltrimethoxysilane (3-APTMS) and N-[3-(trimethoxysilyl)propyl]-ethylenediamine (MSDA) are two amino-functional moieties grafted onto silica surfaces. A maximum copper absorption of 33.45 mg/g was confirmed using the amino-functionalized material at an initial 3-APTMS concentration of 2.52 mmol/g. Silica with a BET surface of 331 m²/g and a pore volume of 1.38 cm³/g demonstrated a good copper absorption capacity. Interference species such as pH, NH₃ and EDTA were also studied in this work.     

Formation of novel mesoporous TiC microspheres through a sol–gel and carbothermal reduction process

Novel mesoporous TiC microspheres with uniform size are synthesized via a sol–gel combined carbothermal reduction process. A microfluidic aerosol nozzle was used to produce droplets which were subsequently dried into gel microspheres under different conditions. The influence of drying temperatures and sol aging time on the diameters of obtained gel microspheres was investigated. The spherical morphology of TiC spheres can be maintained after a two-step heat treatment. Moreover, the TiC microspheres exhibit a high surface area of 267 m²/g and consist of 30–50 nm nano TiC grains and 4.5 nm pores. This unique nanostructure is directly formed from the carbothermal reduction of non-porous and template-free titania/carbon spheres.     

Preparation and characterization of comb type polymer coated poly(HEMA/EGDMA) microspheres containing surface-anchored sulfonic acid: Application in γ-globulin separation

Poly(2-hydroxyethyl methacrylate/ethylenglycol dimethacrylate), poly(HEMA/EGDMA) microspheres was prepared via suspension polymerization. After activation of the hydroxyl groups of poly(HEMA/EGDMA) by bromination, surface-initiated atom transfer radical polymerization (ATRP) of glycidylmethacrylate was conducted in dioxane/bipyridine mixture with CuBr as catalyst at 65 °C. The epoxy groups of the poly(glycidylmethacrylate) comb polymer were converted into sulfonic acid groups (as proton-exchange groups) with reaction of sodium sulfite. Synthesized microspheres were characterized by swelling studies, FT-IR spectroscopy, scanning electron microscopy (SEM) and elemental analysis. The microspheres were used as ion-exchange support for adsorption and purification of human γ-globulin (IgG). The maximum γ-globulin adsorption on the ion-exchange adsorbents was observed at between pH 5.0 and 6.0. The IgG adsorption onto the poly(HEMA/EGDMA) microspheres was negligible. The maximum amount of adsorbed γ-globulin was found to be 230.1 mg/g microspheres. The ion-exchange adsorbents allowed one-step separation of IgG from human plasma. The γ-globulin molecules could be repeatedly adsorbed and desorbed with this ion-exchange support without noticeable loss in their IgG adsorption capacity.     

Hollow core–shell ZnMn2O4 microspheres as a high-performance anode material for lithium-ion batteries

The hollow core–shell ZnMn₂O₄ microspheres are successfully prepared by a solvothermal carbon templating method and then a annealing process. The crystal phase and particle morphology of resultant ZnMn₂O₄ microspheres are characterized by XRD and TEM. The electrochemical properties of the ZnMn₂O₄ microspheres as an anode material are investigated for lithium ion batteries. The results show that the ZnMn₂O₄ microspheres exhibit a reversible capacity of 855.8 mA h g⁻¹ at a current density of 200 mA g⁻¹ after 50 cycles. Even at 1000 mA g⁻¹, the reversible capacity of the ZnMn₂O₄ microspheres is still kept at 724.4 mA h g⁻¹ after 60 cycles. The enhanced electrochemical performance suggests the promising potential of the hollow core–shell ZnMn₂O₄ microspheres in lithium-ion batteries.