Core-shell to Janus morphologies from co-assembly of polyaniline and hydrophobic polymers in aqueous media

In this work, polystyrene (PS) and poly(methyl acrylate) (PMA) with three different molecular weights have been synthesized via reversible addition-fragmentation chain transfer (RAFT) polymerization. Also, polyaniline (PANI) has been synthesized by electrochemical method. The molecular characteristics of synthesized polymers have been investigated by gel permeation chromatography (GPC) and proton nuclear magnetic resonance (H-1 NMR). Both PS and PMA have been co-assembled with PANI in aqueous media at room temperature. Field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), and dynamic light scattering (DLS) have been used to observe the size and morphology of the co-assembled structures. According to results, by increasing molecular weight, hydrophobicity of polymers was increased leading to faster precipitation of micelles in aqueous solution and reduction in the particle size. The results showed that morphology was controlled by thermodynamic factors, and thermodynamically, the morphology that minimizes free energy of the whole surface was the most likely to occur. Moreover, different morphologies from core-shell to Janus structures have been formed.