Methods The multiwalled CNTs were grown at 700°C via a thermal chemical vapor deposition system under the acetylene, nitrogen, and hydrogen ambience. The as-grown CNTs were scraped off from the substrate, and then the derived 0.03-g CNTs were suspended in a mixture of concentrated H2SO4 (95%), HNO3 (70%), and deionized water for 15 min at 140°C to enhance the solubility of CNTs in the following solvents. The filtered CNTs were rinsed by deionized water to remove the acidic residues. Afterwards, these acid-treated CNTs were dissolved in a mixture of ethanol and ethylene Pexidartinib mouse glycol and then ultrasonicated in ice bath for 3 h. After centrifugalizing,

a homogeneous CNT solution with an approximate 0.5-mg/ml concentration of CNTs was sprayed onto glass substrates (Eagle 2000, Corning Display Technologies Taiwan Co., Ltd, Taipei, Taiwan) at 200°C to form the CNTFs. The thickness of CNTF could be adjusted by varying the spray times, and therefore, the 110-nm-thick and 230-nm-thick CNTFs on the glass substrates were obtained, respectively. Subsequently, two glass substrates, one was deposited with CNTF and the other was a bare glass substrate, were face-to-face compressed with a force of 100 N. The thermal

compression temperature was varied from room temperature to 400°C, and the compression duration changed from 0 to 50 min. Results and discussion The field emission scanning electron Selleckchem PLX4032 microscopy (FE-SEM) images of the morphological variations Tozasertib chemical structure for the as-sprayed CNTF and thermally compressed ones are shown in Figure 1. The CNTs in the as-sprayed CNTF can be recognized individually and distributed arbitrarily with the wire shape, as exhibited in Figure 1a.

After the thermal compression with the compression force of 100 N at 200°C for 50 min, the neighbor CNTs seem to be intertwined with each other and each CNT is hard to be distinguished, as shown in Figure 1b. Once the compression temperature Dichloromethane dehalogenase reaches to 400°C, the wire-shaped CNTs no longer exist and the CNTs merge into a continuous film, as shown in Figure 1c. Moreover, from the color contrast in Figure 1c, the surface of CNTF compressed at 400°C becomes much smoother than others. To further realize the effect of the thermal compression on the structure of CNT, the high-resolution transmission electron microscopy (TEM) is executed to analyze the as-sprayed CNTs and thermally compressed ones. For the as-sprayed CNTs shown in Figure 2a, two stacked CNTs are exhibited with the regular and coaxial multiwalled structures, as indicated by the dashed lines. Furthermore, it is easy to distinguish each wall structure even though one CNT stacks on the other.