Biomimetic Nanowire Structured Hydrogels as Highly Active and Recyclable Catalyst Carriers

Nanowire hydrogels with high specific surface areas have great promise in many practical applications. However, the preparation of nanowire hydrogels using common materials and inexpensive means remains an outstanding challenge. This paper reports a novel method for creating aligned nanowire structured hydrogels by directional freezing and γ-radiation initiated polymerization of 2-hydroxyethyl methacrylate (HEMA) using <i>t</i>-butyl alcohol (TBA) as the solvent. The hydrogels prepared at a monomer concentration lower than 2.0 mol L^–1 and a freezing rate higher than 10 mm min^–1 are structured of nanowires, mimicking the microstructure of jellyfish mesogloea. Silver (Ag) nanoparticles (NPs) are introduced into the hydrogels with a chemical reduction method, and the Ag NPs are formed and deposited on the nanowires. Both size and content of Ag NPs in the hydrogels increase with increasing AgNO₃ concentration. The PHEMA and PHEMA/Ag nanocomposite hydrogels all possess very good compressive properties, and the composite hydrogels show higher compressive strengths and excellent deformation recovery. The PHEMA/Ag NPs composite hydrogels show excellent catalytic activity and reusability for the conversion of <i>o</i>-nitroaniline to 1,2-benzenediamine, with an apparent rate constant (<i>k</i>_app) up to 0.165 min^–1. This facile and efficient method can be applied to fabricate more nanowire hydrogels for many practical applications

Additional file 2 of High precision measurement of trace F and Cl in olivine by electron probe microanalysis

Additional file 2. Table S1. Analytical results for trace F and Cl in San Carlos olivine, synthetic olivine and MgO by new EPMA method. Table S2. Analytical results for trace F and Cl in hornblende standards by new EPMA method. Table S3. Analytical results of secondary fluorescence effects of San Carlos olivines mounted in epoxy rensin and tin metal. Table S4. Compositions of (wt%) epoxy-128 used in this study obtained using element analyzer and ion chromatograph. Table S5. Analytical results for trace F and Cl in natural olivine (Ol-1) by new EPMA method. Table S6. Representative compositions (wt%) of antigorite adjacent to olivine sample (Ol-2). Table S7. Representative compositions (wt%) of olivine sample (Ol-2)

Additional file 1 of High precision measurement of trace F and Cl in olivine by electron probe microanalysis

Additional file 1. Fig. S1. Backscattered electron images of synthetic olivine samples. Fig. S2. Backscattered electron images of natural olivine samples. (a) and (b): Ol-1; (c) and (d): Ol-2. Fig. S3. Count rates for F (a) and absorbed beam current (b) for natural Ol-1 olivine sample over 600 s measurements with various beam currents of 400, 600, and 800 nA. The 2 standard deviations of count rates for F for Ol-1 at 400, 600, and 800 nA were 42, 60 and 62 cps, respectively. Count rates for Cl (c) and absorbed beam current (d) for natural Ol-2 olivine sample over 600 s measurements with various beam currents of 400, 600, and 800 nA. The 2 standard deviations of count rates for Cl for Ol-2 at 400, 600, and 800 nA were 26, 30 and 32 cps, respectively. (Accelerating voltage: 20 kV, beam diameter: 5 μm). Fig. S4. Count rates for F (a), Cl (b), and absorbed beam current (c) for Kakanui hornblende standard over 600 s measurements with various beam currents of 400, 600, and 800 nA (Accelerating voltage: 20 kV, beam diameter: 5 μm). The 2 standard deviations of count rates for F for Kakanui hornblende at 400, 600, and 800 nA were 52, 60 and 82 cps, respectively. The 2 standard deviations of count rates for Cl for Kakanui hornblende at 400, 600, and 800 nA were 37, 45 and 51 cps, respectively. Fig. S5. (a) Smoothed averaged accumulated spectral scans of Kakanui hornblende at the F Kα peak using integral and differential mode on CAMECA SXFive microprobe. The second-order Mg Kβ line was minimized using the optimized differential mode compared to the integral mode. Accelerating voltage = 20 kV; beam current = 150 nA; beam diameter = 10 μm; dwell time = 500 ms; step = 10 (Sinθ*105); accumulation number = 5; differential mode: base line = 2300 mV, window = 2170 mV, PC1 analyzing crystal. Fig. S6. Backscattered electron images of San Carlos olivine samples mounted in epoxy resin (a) and tin metal (b). Fig. S7. Secondary fluorescence effects evaluation of Cl in natural olivine (Ol-2) from the boundary antigorite using FANAL computer code in CalcZAF/Standard softwar