Diverse Methods to Nanomanufacture Colloidal Dispersions of Polyaniline without Templates

Abstract

Different methods which could be used to produce colloidal dispersions of polyaniline(PANI) nano-objects without templates are described. While the methods are non-deterministic,different nano-objects (nanospheres, nanofibers, nanobelts, nanorice, nanotubes, nanorods, nanodisks,etc.) can be produced. Those most used are: (i) solution polymerization with steric stabilizers (SPS)to produce nanospheres, (ii) interfacial polymerization (IP) to produce nanofibers and (iii) solutionpolymerization in the presence of additives (SPA) to produce nanotubes. Oxidation of aniline inaqueous solution could produce nanotubes, nanofibers and other shapes by controlling mass trans-port/concentration of reactants, pH, and the presence of oligomers/additives. The different modelsproposed to explain the formation of various nano-objects are discussed. Mechanochemical poly-merization (MCP) could produce nanofibers or nanospheres by controlling the aniline/oxidant ratio.PANI nanospheres of tunable sizes can also be produced by nanoprecipitation (NPT) of preformedPANI from its solutions using an antisolvent. The geometrical constraints to the small nano-objectsmade of high-molecular-weight rigid polymers are described. The conditions to produce nanos-tructures also affect the intrinsic properties of PANI (conductivity, crystallinity, and electroactivity).Selected technological applications of PANI nano-objects manufactured as colloidal dispersionswithout templates are discussed. Based on the reviewed work and models, future lines of work areproposed.