Wet Chemical Synthesis Of Polyaniline Micro / Nano Materials And Their Morphology Control

Polyaniline (PANI) nano-materials have caused extensive attentions in the fields of science and technology, and been a new hotspot of material researches, because they possess the excellences of both conducting polymers and nanomaterials. The chemical synthesis to PANI nanomaterials mainly includes the solid template approach (hard template), the reactive template route, the surfactant-based template-guided polymerization (soft template), the surface growth on the solid, the interfacial polymerization and so on. To date, these researches about PANI focus mainly on the synthesis of PANI nanomaterials, however, there still are not general cognitions in this field about the intrinsic relations between the polymerization courses of aniline and the formations of PANI nanostructures. Herein, we investigate the relationships between the oxidation polymerization of aniline and the growth of PANI nanostructures under the different reaction conditions, such as the aqueous solution without any additive, the acidic or alkaline solutions, the diluted and micellar solutions of surfactant and the interfacial polymerization system, providing the theories to the controlled fabrication of PANI nanostructures.Micromats of PANI nanofibers as a novel hierarchical structure are prepared in water without the aid of any additive. The growth processes of PANI micromats are followed through montoring the different stage of polymerization, based on which a possible formation mechanism is proposed through discussing the polymerization courses. Subsequently, PANI plate-like structures and flower-like hierarchical superstructures are successfully fabricated by the oxidation of aniline with the oxidant/monomer molar ratio varying between 0.1:1 and 0.8:1. With the oxidant/monomer molar ratio between 0.1:1-0.3:1, the plate-like structures can be produced, while the flower-like architectures are obtained at the molar ratio of 0.4:1-0.8:1 by the oxidative polymerization.A low-concentration inorganic-acid solution approach is proposed to fabricate conducting PANI fanlike architectures of rectangular sub-microtubes. Through measuring the growth processes of tube-based fanlike PANI and discussing the oxidation polymerization of aniline, we give the possible interpretations to the formation of PANI rectangular tubes and their fanlike assembly, respectively. When the reaction medium is altered to alkaline solution, nanosheet- or nanorod-based microspheres and nanorod-based microrods of PANI have been successfully fabricated. With the increasing temperature of polymerization, the building blocks of PANI microspheres change from nanosheets to nanorods, accompanied by the appearance of tower-like structures based on nanoplates. The time-dependence morphological evolvement of tower-like hierarchical structures is examined, based on which we discuss their growth courses.PANI rectangular sub-microtubes are successfully produced through the oxidation polymerization of aniline in dilute anionic surfactant (sodium dodecyl sulfate, SDS) solution. The shape (rectangle or square) of cross sections and the uniformity of PANI sub-microtubes can be appropriately adjusted by simply tuning the concentration of aniline monomer and the molar ratio of APS to aniline, respectively. When low-concentration HCl is added into above system, nanostructure-covered rectangular sub-microtubes of PANI can been synthesized by the polymerization of aniline. The influences of temperature and the concentrations of SDS and HCl on the morphology of product are studied in detail, in order to explore the growth mechanism. In the Triton X-100 (TX-100) micellar solution, the poly(aniline-co-pyrrole) (PACP) hollow nanospheres are successfully prepared via the oxidation polymerization of the mixture of aniline and pyrrole. The spherical micelles consisted of TX-100 and co-monomers in the reaction system and the polymerization processes are monitored by dynamic laser-light scattering (DLS) technology. Based on our experiment results, a possible mechanism to PACP hollow nanospheres is speculated to explain the formation. Additionally, FTIR, UV-visible, 1H NMR spectra provide sufficient data to characterize the copolymer chemical structure of PACP.A novel synthesis approach has been developed to fabricate PANI nanomaterials on the glass surface through the aqueous/alcohol interfacial polymerization. Different from the usual interfacial reaction, surfactant is employed as structure-orienting agent to manipulate the propagation and assembly of PANI nanostructures. PANIs with different morphologies, such as belt-like structures, flow-like hierarchical structures, nanosheets, and belt-based marigold-like structures, are tailored with the aid of the hydrogen bonding among polymer, surfactant and alcohol, or the electrostatic interactions between polymer and glass substrate.