Surface-Enhanced Infrared Spectra of Manganese (III) Tetraphenylporphine Chloride Physisorbed on Gold Island Films

Surface-enhanced infrared absorption (SEIRA) spectra of manganese (III) tetraphenylporphine chloride (Mn(TPP)Cl) on metal island films were measured in transmission mode. Dependences of the enhancement factor of SEIRA on both the sample quantity and the type of evaporated metal were investigated by subsequently increasing the amount of Mn(TPP)Cl on gold and silver substrates. The enhancement increases nonlinearly with the amount of sample and varies slightly with the thickness of metal islands. In particular, the SEIRA transmission method presents an anomalous spectral enhancement by a factor of 579, with substantial spectral shifts, observed only for the physisorbed Mn(TPP)Cl that remained on a 3-nm-thick gold film after immersion of the substrates into acetone. A charge-transfer (CT) interaction between the porphyrinic Mn and gold islands is therefore proposed as an additional factor in the SEIRA mechanism of the porphyrin system. The number of remaining porphyrin molecules was estimated by calibration-based fluorescence spectroscopy to be 2.36×1013 molecules (i.e., ~2.910-11 mol/cm2) for a 3-nm-thick gold film, suggesting that the physisorbed molecules distributed very loosely on the metal island surface as a result of the weak van der Waals interactions. Fluorescence microscopy revealed the formation of microcrystalline porphyrin aggregates during the consecutive increase in sample solution. However, the immersion likely redistributed the porphyrin to be directly attached on the gold surface, as evidenced by an absence of porphyrinic microcrystals and the observed SEIRA enhancement. The distinctive red shift in the UV-visible spectra and the SEIRA-enhanced peaks indicate the presence of a preferred orientation in the form of the porphyrin ring inclined with respect to the gold surface.

Nanostructures and nanoporosity in thermoset epoxy blends with an amphiphilic polyisoprene-block-poly(4-vinyl pyridine) reactive diblock copolymer

Nanostructured thermoset blends were prepared based on a bisphenol A-type epoxy resin and an amphiphilic reactive diblock copolymer, namely polyisoprene-block-poly(4-vinyl pyridine) (PI-P4VP). Infrared spectra revealed that the P4VP block of the diblock copolymer reacted with the epoxy monomer. However, the non-reactive hydrophobic PI block of the diblock copolymer formed a separate microphase on the nanoscale. Ozone treatment was used to create nanoporosity in nanostructured epoxy/PI-P4VP blends via selective removal of the PI microphase and lead to nanoporous epoxy thermosets; disordered nanopores with the average diameter of about 60 nm were uniformly distributed in the blend with 50 wt% PI-P4VP. Multi-scale phase separation with a distinctly different morphology was observed at the air/sample interface due to the interfacial effects, whereas only uniform microphase separated morphology at the nanoscale was found in the bulk of the blend.

Tuning the grade of graphene: Gamma ray irradiation of free-standing graphene oxide films in gaseous phase

A direct approach to functionalize and reduce pre-shaped graphene oxide 3D architectures is demonstrated by gamma ray irradiation in gaseous phase under analytical grade air, N2 or H2. The formation of radicals upon gamma ray irradiation is shown to lead to surface functionalization of the graphene oxide sheets. The reduction degree of graphene oxide, which can be controlled through varying the γ-ray total dose irradiation, leads to the synthesis of highly crystalline and near defect-free graphene based materials. The crystalline structure of the graphene oxide and γ-ray reduced graphene oxide was investigated by x-ray diffraction and Raman spectroscopy. The results reveal no noticeable changes in the size of sp2 graphitic structures for the range of tested gases and total exposure doses suggesting that the irradiation in gaseous phase does not damage the graphene crystalline domains. As confirmed by X-ray photoemission spectroscopy, the C/O ratio of γ-ray reduced graphene oxide is increasing from 2.37 for graphene oxide to 6.25 upon irradiation in hydrogen gas. The removal of oxygen atoms with this reduction process in hydrogen results in a sharp 400 times increase of the electrical conductivity of γ-ray reduced graphene oxide from 0.05 S cm-1 to as high as 23 S cm-1. A significant increase of the contact angle of the γ-ray reduced graphene oxide bucky-papers and weakened oxygen rich groups characteristic peaks across the Fourier transform infrared spectra further illustrate the efficacy of the γ-ray reduction process. A mechanism correlating the interaction between hydrogen radicals formed upon γ-ray irradiation of hydrogen gas and the oxygen rich groups on the surface of the graphene oxide bucky-papers is proposed, in order to contribute to the synthesis of reduced graphene materials through solution-free chemistry routes.

Microencapsulation of tuna oil fortified with the multiple lipophilic ingredients vitamins A, D3, E, K2, curcumin and coenzyme Q10

Complex coacervates of gelatin and sodium hexametaphosphate (SHMP) was used to microencapsulate tuna oil fortified with the multiple functional lipophilic ingredients, vitamin A, D3, E, K2, curcumin and coenzyme Q10. An emulsion homogenization speed of 15,000 rpm for 15 min resulted in low surface oil content (0.08%), high encapsulation efficacy (99.84%) and encapsulation yield (96.59%), with a significantly enhanced oxidative stability index (6.23 h). The Fourier transform infrared spectra showed that there was no observable oxidation of the oil during microencapsulation. This study shows that microencapsulation using complex coacervation is suitable for stabilizing multiple bioactive lipophilic ingredients.

Conductive polymer coatings

Conducting polymer-coated textiles possess a wide range of electrical properties. The surface resistivity is influenced by concentrations of the reactants, the thickness of the coating, the nature of the substrate surface, the extent of penetration of the polymer into the textile structure, and the strength of the binding of the coating to the textile surface. Low resistivity in fabric results from highly doped thicker coatings that penetrate well into the textile structure, thus enabling good electrical contact between fibers. Microwave studies showed that conductive textiles are not highly effective as electromagnetic shielding materials owing to their medium-level conductivity and therefore large skin depth. Combined with the fact that coatings are around 1. ?m thick, they cannot act as effective reflective barriers to electromagnetic radiation. However, because they are highly absorptive in the microwave region, absorbing materials can be designed in conjunction with conductive textiles. Study of Fourier transform-infrared spectra of aged polypyrrole films has shown an increase in intensity of an ?,?-unsaturated conjugated carbonyl peak that may be linked to the increase in resistance but cannot be the only factor, because the rate of electrical decay was influenced by several factors such as temperature, the type and concentration of the dopant, and the aging time, all of which signify a complex mechanism of degradation of conductivity. Degradation is a major concern for conductive textile systems that needs to be characterized before considering these materials for potential applications.

Mechanical ageing performance of minimalist and traditional footwear foams

The aim of this study was to obtain a fundamental understanding of how running shoe midsole foam thickness contributes to footwear degradation using the heel and forefoot regions of traditional (TS) and minimalist (MS) running shoes. We hypothesized that ethylene vinyl acetate (EVA) foam midsole material properties and footwear degradation performance under a biofidelic mechanical ageing protocol would differ as a function of shoe type and thickness. Attenuated totalreflectance Fourier transform infrared spectra indicated that the foam chemical compositions were similar and confirmed that all midsoles were composed of EVA copolymer. Differences in density and cell size were detected between shoes and thicknesses. MS foam was uniformly high density (rMS D 240 kg/m3), while TS foam consisted of two co-molded layers with forefoot density (rTS-FF D 250 kg/m3) greater than heel (rTS-H D 160 kg/m3). Relative density and cell size values were generally proportional and inversely proportional to density, respectively. Degradation from mechanical ageing was greatest in the first 2 km of ageing, with the full ageing (21 km) resulting in an average 54% loss of energy absorption. Regardless of shoe type or foam microstructure, thicker and softer heel foams absorbed 83% more energy but degraded ata 49% faster rate. The fact that the heel degraded more rapidly than forefoot caused the drop to decrease at an equivalent rate for both shoe types. Overall, thickness was a greater predictor of average performance than microstructure variables for the present footwear conditions. However, the apparent drawback of thicker foam was exemplified by heel samples, which underwent a 1.4 mm greater loss of thickness and lost 550 mJ more energy absorption than forefoot samples.

Photocatalytic degradation of bisphenol A by HMS/g-C3N4 composite

In this work, hexagonal mesoporous silica/g-C3N4 (HMS/C3N4) was synthesized by heating a mixture of self-prepared HMS and dicyandiamide. The as-prepared materials were characterized by transmission electron microscopy (TEM), X-ray diffractometer (XRD), Fourier transform infrared spectra (FT-IR) and Brunauer–Emmett–Teller analysis (BET). The prepared photocatalysts were applied to decompose bisphenol A (BPA) under UV light illumination. The mass ratios of HMS to melamine were optimized. The results showed that optimal mass ratios HMS to dicyandiamide was 1:1. Even though with the same catalyst dosage (1.0 g/L), the degradation kinetic rate constant of BPA over HMS/C3N4 (0.00526 min−1) was 1.76 times and 1.4 times than those on P25 (0.00298 min−1) and pure C3N4 (0.00383 min−1), while the rate constant of photolysis was only 0.00021 min−1. The enhanced photocatalytic activity of the HMS/C3N4 composite was ascribed to higher specific surface area and less aggregation compared to the pure C3N4. It is feasible and efficient to degrade BPA by HMS/C3N4 composite, which is easier to be separated than pure C3N4 after the pollutant has been removed completely.

Characterization of supported cylinder-planar germanium waveguide sensors with synchrotron Infrared radiation

Cylinder-planar Ge waveguides are being developed as evanescent-wave sensors for chemical microanalysis. The only non-planar surface is a cylinder section having a 300-mm radius of curvature. This confers a symmetric taper, allowing for direct coupling into and out of the waveguide's 1-mm² end faces while obtaining multiple reflections at the central <30-μm-thick sensing region. Ray-optic calculations indicate that the propagation angle at the central minimum has a strong nonlinear dependence on both angle and vertical position of the input ray. This results in rather inefficient coupling of input light into the off-axis modes that are most useful for evanescent-wave absorption spectroscopy. Mode-specific performance of the cylinder-planar waveguides has also been investigated experimentally. As compared to a blackbody source, the much greater brightness of synchrotron-generated infrared (IR) radiation allows a similar total energy throughput, but restricted to a smaller fraction of the allowed waveguide modes. However, such angle-selective excitation results in a strong oscillatory interference pattern in the transmission spectra. These spectral oscillations are the principal technical limitation on using synchrotron radiation to measure evanescent-wave absorption spectra with the thin waveguides.