Bifunctional polyaniline electroconductive hydrogels with applications in supercapacitor and wearable strain sensors.

In this article, bifunctional polyaniline/polyacrylamide (PANI/PAAm) hydrogel is fabricated. The hydrogel has capacitive performance and can be used for monitoring human motions. The effect of PANI doped with two different acids on the properties of hydrogels was researched. The first type of PANI hydrogel is doped with hydrochloric (HCl) and the second one with p-toluenesulfonic acid (PTSA). One application of these two kinds of hydrogels was prepared to serve as solid electrolytes in supercapacitors with sandwich structure. The sandwich structure was constructed by introducing two PANI film parts reinforced on both sides of the PANI hydrogel. Supercapacitors with sandwich structure possess areal capacitance of 635 mF/cm2 (HCl-PANI hydrogel) and 1022 mF/cm2 (PTSA-PANI hydrogel). In this structure, PANI hydrogel provides channels for ion transport as a solid electrolyte. In addition, the PANI hydrogel can be utilized as the sensitive sensors as well. By employing I-v curve and I-t curve to characterize the performance of the sensor, the hydrogel material can be used as a wearable sensor with sensitivity to slight deformation. This is a sensitive sensor that it can respond to the speed and amplitude of the bending movement of the arm. The effective bifunctional property results indicate that the hydrogel, capacitive and conductive PANI hydrogel has great piezoelectric sensitivity as the sensors, which has become promising materials for wearable sensors and solid electrolytes.

Supramolecular self-assembly of three-dimensional polyaniline and polypyrrole crystals.

Herein, we first report a novel approach for preparing 3D π-π stacked crystals of polyaniline and polypyrrole and show how they self-assemble in a suitable solution environment. 3D crystals of polyaniline and polypyrrole show high charge-transport properties of 130 S cm(-1) and 150 S cm(-1), respectively. Remarkably, the 3D crystals of polyaniline obtain excellent anisotropic conductivity.

Hierarchical self-assembly of hexagonal single-crystal nanosheets into 3D layered superlattices with high conductivity.

While the number of man-made nano superstructures realized by self-assembly is growing in recent years, assemblies of conductive polymer nanocrystals, especially for superlattices, are still a significant challenge, not only because of the simplicity of the shape of the nanocrystal building blocks and their interactions, but also because of the poor control over these parameters in the fabrication of more elaborate nanocrystals. Here, we firstly report a facile and general route to a new generation of 3D layered superlattices of polyaniline doped with CSA (PANI-CSA) and show how PANI crystallize and self-assemble, in a suitable single solution environment. In cyclohexane, 1D amorphous nanofibers transformed to 1D nanorods as building blocks, and then to 2D single-crystal nanosheets with a hexagonal phase, and lastly to 3D ordered layered superlattices with the narrowest polydispersity value (M(w)/M(n) = 1.47). Remarkably, all the instructions for the hierarchical self-assembly are encoded in the layered shape in other non-polar solvents (hexane, octane) and their conductivity in the π-π stacking direction is improved to about 50 S cm(-1), which is even higher than that of the highest previously reported value (16 S cm(-1)). The method used in this study is greatly expected to be readily scalable to produce superlattices of conductive polymers with high quality and low cost.