Oxidative polymerization of para-substituted styrene derivatives: Synthesis, characterization and kinetics study

Synthesis and characterization of four new polymeric peroxides of styrene monomers with substituents in the para-position are discussed. NMR spectroscopy and elemental analysis confirm the alternating copolymer structure with peroxy bonds in the backbone. The thermal degradation of the polyperoxides has been studied by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The measured highly exothermic heat of degradation of these polymers is nearly the same as that of poly(styrene peroxide). Electron-impact mass spectroscopy (EI-MS) supports alternating peroxide units in the polymer chain. Kinetics of oxidative polymerizations have been studied for various para-substituted styrene monomers in toluene in the presence of a free radical initiator 2,2′-azobisisobutyronitrile (AIBN) at 40–50 °C and 100 psi oxygen pressure. Interestingly, both electron-withdrawing and electron-donating substituent groups in the para-position increases rate of oxidative polymerization. Theoretical studies have been performed using density functional theory (DFT) to support the order of oxidation rates.