Diaminium salt as reactive amphiphile for the synthesis of poly(m-phenylenediamine) and paraffin microencapsulation

Abstract

Poly(m-phenylenediamine) (PmPDA) was synthesized via an oxidative polymerization using benzene-1,3-diaminium dodecyl sulfate (P2) as the monomer. P2 is a new concept of reactive surfactant because, unlike conventional polymerizable surfactants where the polymerizable group is a carbon–carbon double bond, therein, the polymer chain propagates through the diaminium group. Polymerization in aqueous micellar solution, chloroform/water interface, and xylene/water emulsion allowed successful synthesis of PmPDA. Infrared and UV–vis spectroscopy revealed that PmPDA share chemical structure, based on phenazine with open segments, rich in quinoid rings (pernigraniline-like), and partially doped, regardless of the method of synthesis. Conversely, electron microscopy exhibited important effect on morphology (nanofibers, pot-like, and globular nanoparticles) as a function of polymerization method and temperature. Additionally, cyclic voltammetry indicated electroactivity in all products, showing reduced/semi-oxidized and semi-oxidized/oxidized redox transitions with differences concerning synthesis method and temperature. A paraffin/PmPDA core–shell composite was obtained by emulsion polymerization method taking advantage of P2 amphiphilic properties. Electron microscopy evidenced microencapsulation, whereas thermal properties (melting temperature, melting enthalpy, thermal stability, and viscosity as function of temperature) suggested promising properties for the design of form-stable phase change materials.