Water-soluble Aniline/o-Anisidine Copolymer: Enzymatic Synthesis and Characterization

The synthesis of aniline/o-anisidine copolymer was described by enzymaticallyoxidative polymerization of aniline (An) and o-anisidine (As) using poly(sodium4-styrene sulphonate) (SPS) as a template. The enzyme horseradish peroxidase(HRP) was used as a catalyst with a stoichiometric amount of hydrogen peroxide as anoxidant at pH 4.3 in 0.01 M sodium phosphate buffer solution medium. The UV-visspectra of An/As copolymer (1:1) exhibited more similarity to the spectral features ofo-anisidine. To address the effect of monomer ratio in the synthesized copolymer, thepolymerization was carried out in different ratios of o-anisidine to aniline. The resultantAn/As copolymer was characterized by FTIR and UV-vis techniques. The resultsshowed that the enzymatic polymerization produced a real copolymer containinganiline and o-anisidine units. The similarity of the UV-vis spectra of the copolymer toenzymatically synthesized poly(o-anisidine) confirmed that the amount of monomericunit of o-anisidine was higher than aniline. This was due to a much higher reactivity ofthe former. Thus, as expected, this copolymer spectral characteristics were moresimilar to the enzymatically synthesized poly(o-anisidine). UV-Vis and FTIR spectraconfirmed that the undoped form of An/As copolymer, unlike the chemically synthesizedcopolymer, has formed a complex with SPS. This biomimetic approach offered anunsurpassed easiness in the synthesis, processability, stability and environmentalcompatibility.