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Abstract:The two blocks of a polystyrene-block-poly(2-cinnamoylethyl methacrylate), PS-b-PCEMA, sample, with 1.25 Â 10 3 styrene and 158 CEMA units, segregate in bulk films. PCEMA forms cylinders that disperse in the continuous matrix of PS when annealed at 110 AE 28C. UV photolysis cross-linked the PCEMA cylinders. Separating the cross-linked PCEMA cylinders by dissolving PS in toluene or THF yielded isolated nanofibers with PCEMA core and PS shell. Light scattering studies in toluene or chloroform revealed that the nanofibers were wormlike with a persistence length of $ 400 nm, a molar mass exceeding 10 10 g mol À1, and a radius of $ 43 nm. The nanofibers formed lyotropic liquid crystalline phases in bromoform and the order ± disorder transition temperature of the liquid crystals increased with nanofiber concentration.

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Hydrogen damage is a severe problem that refers to the degradation of mechanical properties of a metal caused by the presence of, or interaction with, hydrogen. The reduction of hydrogen ions is a source of atomic hydrogen. Hence, corrosion reactions, the application of cathodic protection and electroplating, etc., are major sources for introducing hydrogen into metals. During these hydrogen-generating processes, some of the reduced hydrogen may be absorbed on the metal surface and diffuse into the metals. [1][2][3][4][5] The presence of hydrogen in metals has a significant influence on the mechanical properties and electrochemical behavior of metals. For instance, increased hydrogen content results in the low stress fracture and plastic reduction of steels. 6,7 Dissolution of hydrogen in metals was proven to affect the general corrosion of metals 1,8 and to induce stress corrosion cracking 9,10 and pitting corrosion. 11,12 It is known that the nature of passive films on metals and alloys is an ultimate factor which controls their corrosion behavior. 13,14 Therefore, knowledge about electronic structure of the passive film is required for better understanding of the corrosion process. For this reason, much work has been devoted to the study of the electronic properties and chemical composites of passive films on metals and alloys. 13,[15][16][17][18][19] Most passive films formed on stainless steels behave like semiconductors. Based on the fact that the potential-dependent transpassive dissolution varies with the electronic properties of the passive film, Sato 20 proposed a breakdown mechanism of the passive film on metals: the electrochemical stability of a passive film strongly depends on the electron energy band structure in the film. Bohni, et al. 21 studied the semiconductive properties of the passive films on 304 SS using Mott-Schottky analysis and photoelectrochemical methods. They found the coincidence of the onset potential for pit nucleation with the flatband potential of passive film. Bianchi et al. 14 concluded that the high susceptibility of stainless steel to pitting nucleation was connected to n-type conductivity of the oxide film. Nevertheless, the reason for the existence of this correlation is still not clear, and little research has been done to investigate the effect of hydrogen dissolved in metals on electronic structures of passive films on metals. 22 In this work, the new experimental results on the reversion of the electronic properties of passive film induced by hydrogen dissolved in AISI 310 SS were presented. The experimental results were analyzed by taking into account the susceptibility of specimens to pitting corrosion with or without hydrogen and were interpreted by the band model of different conductivity types of passive films. ExperimentalThe test material was commercial 310 SS foil, 0.01 cm thick. The main composition (wt %) was 23.5 Cr, 18.4 Ni, 1.76 Mn, 0.70 Si, 0.15 Mo, 0.16 Cu, 0.09 Ti, 0.02 Nb, 0.06 C, 0.02 P, 0.02 S, and Fe in balance. The solution for hydrogen charging wa...

Surface energy plays an important role in surface physics, [1,2] biophysics, [3,4] surface chemistry, [5,6] and catalysis. [7] A gradient of surface energy between a solid and liquid interface can induce transport of liquids [8][9][10][11] and water running uphill, [12] which is important for DNA analysis devices.[13] Due to the 2D nature and relatively few molecules or atoms involved, the density of surface energy is usually quite small, which is impractical for utilizing surface energy as an energy source. Nevertheless it is attractive to use surface energy at the nanoscale because of the lower power consumption for nanodevices and the higher specific surface area for nanomaterials. [14][15][16][17][18] In this work, we demonstrate an effective design of single-walled carbon nanotubes (SWNTs) to harvest surface energy of ethanol and convert it into electricity. In this ethanol-burner-like design, an open-circuit voltage (V oc ) can be obtained as a result of ethanol flow in the capillary channels formed among SWNTs driven by surface tension. The V oc remains constant as long as there is ethanol from the source. The maximum power can be up to $1770 pW per device and can serve as a self-powered system to drive a thermistor. Meanwhile, the performance (the inducing rate of V oc , the value of V oc , and the output power) can be significantly enhanced by the Marangoni effect. [19] SWNTs were synthesized by floating catalytic chemical vapor deposition and treated by diamond wire drawing dies, [20][21][22] which results in well-aligned individual SWNTs (see Supporting Information S1). The resulting SWNT rope ($25.0 mm (length) Â 0.6 mm (diameter), Fig. 1a) is connected to electrodes of aluminum film, forming a suspended structure on a glass slide. The device is measured by a Keithley 4200-SCS, semiconductor characterization system, (voltage resolution 1 mV) and the dynamic characteristics of the open-circuit voltage (V oc ) are monitored while adding ethanol (MOS grade, 99.9%) to the beaker (Fig. 1b, see Supporting Information S2).In an open beaker, no obvious V oc is observed at the beginning (angle 408, Fig. 2a). When the ethanol level reaches the SWNT rope, the V oc begins to increase. The increase of V oc is almost linear from zero to 200 mV for the first 240 s, then the V oc saturates gradually at 219 mV where is remains constant over 6 h as shown in Figure 2a. V oc can remain constant as long as the ethanol level is contacting the SWNT rope. When the beaker is covered as indicated by region 2 (Fig. 2b), V oc will gradually decrease back to the original value. This process can be repeated COMMUNICATION www.MaterialsViews.com www.advmat.de Figure 1. The SWNT device and schematic layout of the experimental setup. a) An image of the device with a suspended SWNT rope. After treating with diamond wire drawing dies, the SWNT rope has a diameter of $0.6 mm and length of $25.0 mm and is connected to the electrodes. b) When measuring, the device is placed into a beaker with an angle between the SWNT rope and the ethanol ...

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