Synthesis and characterization of alternating copolymers of thiophene-containing N-phenyl maleimide and styrene by photoinduced radical polymerization and their use in electropolymerization

A novel N-(4-(3-thienyl methylene)-oxycarbonylphenyl) maleimide (MBThi) monomer was synthesized by the esterification reaction of maleimidobenzoic acid (MBA) with 3-thiophene methanol. Photoinduced radical polymerization was employed to prepare the alternating copolymers of MBThi with styrene (St) at room temperature using ω,ω-dimethoxy-ω-phenylacetophenone (DMPA) as photoinitiator. Different copolymerization conditions were examined to estimate the influence of the used solvents and comonomers' total molar concentration on the conversion, the number-average molecular weight (M_n), and polydispersity index (M_w/M_n) of the resulting polymers. Thermal behavior of the alternating copolymers (PSt-alt-MBThi) was also investigated by thermogravimetrical analysis (TGA) and differential scanning calorimetry. Moreover, the obtained alternating copolymers were employed in electropolymerization experiments and random conjugated graft copolymers with thiophene or pyrrole were synthesized through their pendant thienyl groups. These polymers were characterized by cyclic voltammetry (CV), FTIR and scanning electron microscopy (SEM). Conductivity measurements were carried out by the four-probe technique.