Synthesis and characterization of novel methacrylic copolymers: Determination of monomer reactivity ratios

A new methacrylic monomer, 4-nitro-3-methylphenyl methacrylate (NMPM) was prepared by reacting 4-nitro-3-methyl phenol dissolved in methyl ethyl ketone (MEK) in the presence of triethylamine as a catalyst. Copolymerization of NMPM with methyl methacrylate (MMA) has been carried out in methyl ethyl ketone (MEK) by free radical solution polymerization at 70 +/-+ VC utilizing benzoyl peroxide (BPO) as initiator. Poly (NMPM-co-MMA) copolymers were characterized by FT-IR, H-1-NMR and C-13-NMR spectroscopy. The molecular weights (M-w and M-n) and polydispersity indices (M-w/M-n) of the polymers were determined using a get permeation chromatograph. The glass transition temperatures (T,) of the copolymers were determined by a differential scanning calorimeter, showing that T-g increases with MMA content in the copolymer. Thermogravimetric analysis of the polymers, performed under nitrogen, shows that the stability of the copolymer increases with an increase in NMPM content. The solubility of the polymers was tested in various polar and non-polar solvents. Copolymer compositions were deter-mined by H-1-NMR spectroscopy by comparing the integral peak heights of well separated aromatic and aliphatic proton peaks. The monomer reactivity ratios were determined by the Fineman-Ross (r(1) = 7.090:r(2) = 0.854), Kelen-Tudos (r(1) = 7.693: r(2) = 0.852) and extended Kelen-Tudos methods (r(1) = 7.550: r(2)= 0.856).