We report the template-guided synthesis of water-soluble chiral conducting polymer nanocomposites. This synthetic route is facile and can be carried out on a large scale easily. Synthesis of water-soluble polyaniline nanocomposites is achieved by careful control of experimental parameters such as acid concentration, ionic strength, monomer/template ratio, total reagent concentration, order of reagent addition, temperature, and timing. Here, we show that a chiral polyaniline nanocomposite can be synthesized by addition of a chiral inducing agent (chiral acid) prior to polymerization and that the enantioselectivity of polyaniline can be controlled by the addition of the (+) or (-) form of the chiral acid. Further, we show that varying the chiral acid and/or salt concentration has a dramatic impact on the degree of chirality in the final polymer nanocomposite. The polyaniline nanocomposites were characterized by UV-vis, infrared (IR), circular dichroism spectroscopy, and tunneling electron microscopy. IR spectra show that the polyaniline and the template are intimately mixed at the molecular level. The strong polyaniline/template interaction results in nanocomposite chirality that is robust through repeated doping and dedoping cycles.

We report the synthesis and characterization of polyaniline integrally skinned asymmetric membranes (PANI ISAMs) and their use as chemical and electrochemical actuators. SEM characterization of a PANI ISAM cross section showed a thin dense skin and a microporous substructure with a PANI density gradient. The deformation mechanism of chemical monolithic PANI ISAM actuation was found to result mainly from asymmetric volume expansion/contraction because of the presence/absence of counterions during PANI doping/dedoping cycles. Actuator performance was affected by acid concentration and film thickness. Our results also show that the deformation mechanism in electrochemical PANI ISAM actuation involves mainly changes in polymer conformation with changes in oxidation state. Because these PANI ISAM actuators are monolithic, that is, they are fabricated without any additional layer (tape, polymer, or gold), their structural stability is expected to be superior to bimorph actuators.

Previously we reported synthesis and characterization of water-soluble chiral conducting polymer nanocomposites via template-guided synthesis. Experimental procedures and parameters need to be carefully controlled to achieve synthesis of water-soluble nanocomposites. Here, we describe a modified synthetic procedure with higher molecular weight poly(acrylic acid) (PAA) (MW ∼ 250 000) as a template. This new system allows synthesis of chiral water-soluble nanocomposites over a more broad range of conditions making the synthesis more reproducible and easier to carry out at large scale. Another objective of this work is to further understand the underlying formation mechanism of chiral polyaniline nanocomposites. We carried out a detailed study of how temperature, template, and solvent affect the final morphology and properties of these nanocomposites. We found that the extent of interaction and stability of the template/monomer/acid adduct (nanocomposite precursor) and population density of monomer surrounding the template are crucial in determining the degree of nanocomposite chirality. Detailed characterization of the nanocomposites and their precursors was carried out by circular dichroism (CD), UV-vis, FTIR, NMR, and TEM spectroscopy. On the basis of experimental results and synthetic procedures, a simplified model for the formation mechanism of chiral polyaniline nanocomposite is proposed.