Synthesis and characterisation of water dispersible copolymer submicron spheres of poly-(phenylenediamine-co-N-sulfopropyl aniline) via random copolymerisation

Abstract

The homopolymers of poly-phenylenediamines (P-PD's) and poly-N-sulfopropyl aniline (PSPA) were synthesized via chemical oxidative polymerization of phenylenediamine monomers and sulfopropyl aniline using ammonium persulfate as oxidizing agent in acidified medium. Three homopolymers of phenylenediamines synthesised were poly (m-phenylenediamine) P-MPD, poly (p-phenylenediamine) P-PPD and poly (o-phenylenediamine) P-OPD. Poly-N-sulfopropyl aniline (PSPA) is a self doped water soluble conducting polymer. Random copolymerization of N-sulfopropyl aniline and phenylenediamines would enhance the solubility of the copolymer nanomaterials. Three different copolymer compositions (COP25, COP50 and COP75) were employed for copolymer synthesis based on weight percentage of co-monomer's feed taken. Homopolymers and copolymers were characterized by fourier-transform infrared spectroscopy (FT-IR) and elemental analysis. The UV–Visible absorption spectra of the samples in water were shown the characteristic polaron- π* and π−π* peaks. The solid state ordering of the samples recorded by powder wide angle x-ray diffraction studies reveals that homopolymer samples were partially crystalline, whereas copolymers were either amorphous or less crystalline than homopolymer. Morphological features of the polymers and copolymers were recorded by scanning electron microscope (SEM). Poly (m-Phenylenediamine) was present as uniformly distributed submicron spheres with an average size of 850 ± 50 nm, whereas the poly (p-phenylenediamine) was present as non-uniform spheres with size in the range 600 ± 100 nm. The P-OPD sample was highly crystalline and it has shown some ordered rod like structures. Interestingly, all copolymer samples like M-COP25, P-COP25, and O-COP25 were formed as uniform submicron spheres. Poor water solubility of poly-phenylenediamines in aqueous solution was increased tremendously upon copolymerization.