Tsao-Li Chuang

Synergistic effects of hydrophobicity and gas barrier properties on the anticorrosion property of PMMA nanocomposite coatings embedded with graphene nanosheets

In this paper, the surface of a PMMA/graphene nanocomposite (PGN) with biomimetic hydrophobic structures was first prepared by the nanocasting technique and applied in corrosion protection coatings. First of all, a transparent soft template with negative patterns of a Xanthosoma sagittifolium leaf can be fabricated by thermal curing of the polydimethylsiloxane (PDMS) pre-polymer in molds at 60 °C for 4 h, followed by detaching the PDMS template from the surface of the natural leaf. Subsequently, PGN with a hydrophobic surface (HPGN) of the biomimetic natural leaf was fabricated, using PDMS as the negative template, through casting onto a cold rolled steel (CRS) electrode. The surface morphology of as-synthesized hydrophobic PMMA (HP) and PGN coatings was found to show lots of micro-scaled mastoids, each decorated with many nano-scaled wrinkles, which were investigated systematically by scanning electron microscopy (SEM). The contact angle (CA) of a water droplet on the sample surface can be increased from ∼80° for the PMMA surface to ∼150° for HP and HPGN and the sliding angle (SA) decreased from ∼60° to 5°. The morphological studies of the dispersion capability of graphene nanosheets (GNSs) in the polymer matrix can be carried out by observation under a transmission electron microscope (TEM). It should be noted that HPGN coating was found to reveal an advanced corrosion protection effect on the CRS electrode as compared to that of neat PMMA and HP coatings based on a series of electrochemical corrosion measurements in a 3.5 wt% NaCl electrolyte. The enhancement of corrosion protection of HPGN coatings on the CRS electrode could be interpreted by the following two possible reasons: (1) the hydrophobicity repelled the moisture and further reduced the water/corrosive media adsorption on the epoxy surface, preventing the underlying metals from corrosion attack, as evidenced by contact angle (wettability) measurements. (2) The well-dispersed GNSs embedded in the HPGN matrix could hinder corrosion due to their relatively higher aspect ratio than clay platelets, which further effectively enhance the oxygen barrier property of HPGN, as evidenced using a gas permeability analyzer (GPA).

Polyaniline/carbon nanotube nanocomposite electrodes with biomimetic hierarchical structure for supercapacitors

Polyaniline (PANI)/multi-walled carbon nanotube (MWNT) nanocomposite films with three-dimensional architectures on the surface were prepared using fresh plant leaves as a template through the nanocasting technique. The biomimetic surface morphology of the PANI nanocomposite electrodes, including multiscale papilla-like and nanoscale texture, were successfully replicated from Xanthosoma sagittifolium leaves. The morphology, roughness and dispersed MWNTs of the PANI/MWNT nanocomposites were characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy and atomic force microscopy. It was found that the well-dispersed MWNTs and the multiscale morphology formed a uniform nanocomposite, with an observed larger surface area, high specific capacitance and good cycling stability during the charge–discharge process. A specific capacitance as high as 535 F g−1 at a current density of 1 A g−1 was achieved for a 5 wt% MWNT loading coupled with the high roughness of the PANI nanocomposite, and the capacitance was maintained with the increment of the current density to 3 A g−1. These easily fabricated PANI nanocomposite electrodes show great potential for energy storage applications.

3D-bioprinting approach to fabricate superhydrophobic epoxy/organophilic clay as an advanced anticorrosive coating with the synergistic effect of superhydrophobicity and gas barrier properties†

Correction for ‘3D-bioprinting approach to fabricate superhydrophobic epoxy/organophilic clay as an advanced anticorrosive coating with the synergistic effect of superhydrophobicity and gas barrier properties’ by Chi-Hao Chang et al., J. Mater. Chem. A, 2013, 1, 13869–13877.