Copolymerization of 2-(4-tert-butylphenoxy)-2-oxo-ethyl Methacrylate with Methyl Methacrylate and Styrene: Synthesis, Characterization, and Monomer Reactivity Ratios

A tertierbutylphenoxy group containing methacrylate based monomer 2-(4-tert-butylphenoxy)-2-oxo-ethyl methacrylate (TBPOEMA) was synthesized by reacting 4-tertierbutylphenyl chloroacetate (TBPClAcO) with sodium methacrylate in acetonitrile. TBPClAcO was prepared by reacting tertierbutylphenol dissolved in benzene with chloroacetylchloride. The free-radical-initiated copolymerization of TBPOEMA, with methyl methacrylate (MMA) and styrene (ST) was carried out in dimethylsulphoxide (DMSO) solution at 65°C using 2,2-azobisisobutyronitrile (AIBN) as an initiator with different monomer-to-monomer ratios in the feed. The monomer TBPOEMA and copolymers were characterized by FTIR, ¹H- and ¹³C-NMR spectral studies. The copolymer composition obtained from the ¹H-NMR spectra led to the determination of reactivity ratios. The reactivity ratios of the monomers were determined by the application of Finemann–Ross and Kelen–Tüdös linear methods and the Behnken nonlinear least-squares method. The analysis of reactivity ratios revealed that MMA and ST are more reactive than TBPOEMA, and copolymers formed are statistical in nature. The molecular weights _w and _n) and polydispersity index of the polymers were determined using gel permation chromagtography. Thermogravimetric analysis of the polymers reveal that the thermal stability of the copolymers increases with an increase in the mole fraction of TBPOEMA in the copolymers. Glass transition temperatures of the copolymers were found to decrease with an increase in the mole fraction of TBPOEMA in the copolymers. The apparent thermal decomposition activation energies (E _d) were calculated by Ozawa method using the SETARAM Labsys TGA thermobalance.