AsianScientist (Jul. 14, 2015) – Chemists at Pohang University of Science and Technology (POSTECH) have discovered an innovative method to form two-dimensional polyaniline (PANI) nanosheets using ice as a hard template. Their results have been published in Angewandte Chemie and highlighted as a ‘Highly Important Paper’ by the journal.
The product, called PANI-ICE, is reported to have distinctly outstanding electrical properties of low resistivity and high conductivity. PANI-ICE nanosheets show high electronic current flows twice as high as that of graphene and over 40 times higher conductivity than PANI materials produced by existing established synthetic procedures.
Among various conducting polymers, PANI has long been a promising candidate for practical applications, in particular for microelectronics and battery electrodes, due to its relatively simple chemical synthesis and easy doping process at a low financial and environmental cost compared to other materials.
As PANI’s electrical properties are known to largely depend on its structure, previous studies have focused on the successful fabrication of two-dimensional PANI nanosheets using graphene oxide (GO) as a hard template.
Despite improved electrical properties, however, the high cost, complexity of synthetic procedures and unreliability of electrical properties over a large area are pointed out as the downside of PANI-GO composite nanosheets. Difficulties in removing the graphene oxide template also hinder versatile formation of the products.
In the present study, Dr. Park Moon Jeong, a professor of the Department of Chemistry at POSTECH, and her two doctoral students, Il Young Choi and Joungphil Lee, present an innovative method that effectively overcomes the disadvantages of existing approaches.
Park and colleagues fabricated PANI nanosheets on a smooth surface of deep frozen ice, causing preferential vertical growth and molecular orientation of PANI that significantly enhances its electrical properties.
The superior conductivity of PANI-ICE, in particular, outperforms that of any other existing PANI ever reported. Moreover, the fabricated nanosheets can be easily transferred to various types of substrates as they float off on the surface of an ice template. It is also noteworthy that nanosheets can be patterned into any shape when using prearranged masks.
By simply introducing an easily removable, environment-friendly ice template, the researchers have successfully tackled a major challenge in the commercialization of conducting polymers, namely, improving both electrical properties and processability. Furthermore, Park’s approach allows the synthesis of a large area of PANI in only a few minutes at a cost of less than US$8 per square meter.
“We believe that these unique, unprecedented advantages of PANI-ICE can expedite the eventual convenient and inexpensive application of conducting polymers in versatile electronic devices,” said Park.
The researchers next plan to experiment on small pitch sizes of the nanosheets and further develop their research on the applications for electrodes in various electronic devices such as actuators.
The article can be found at: Choi et al. (2015) High-Conductivity Two-Dimensional Polyaniline Nanosheets Developed on Ice Surfaces.
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Source: Pohang University of Science and Technology; Photo: Erich Ferdinand/Flickr/CC.
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