Abstract
The free-radical initiated copolymerizations of methyl methacrylate (MMA) with 2-ethoxyethyl methacrylate (2-EOEMA) were carried out using 2,2-azo-bisisobutyronitrile (AIBN) as the initiator in 1,4-dioxane solutions. The co- polymer products were characterized by IR, 1 H-NMR, and 13 C-NMR spectroscopic techniques. The reactivity ratios of the monomers were computed by the Fineman-Rose (F-R) and Kelen-Tudos (K-T) methods at lower conversion, using the IR data. The results are in good agreement with each other and the mean reactivity ratios for MMA/EOEMA copolymers are r1=0.8436, r2= 0.7751, and r1r2 = 0.6614. The reactivity ratios indicate the formation of random copolymers, which have been supported by the azeotropic composition evaluations. The distribution of monomer sequence along the copolymer chain has been calculated using a statistical method based on the reactivity ratios. The probability of finding the mean sequence lengths of 2-EOEMA and MMA units has also been evaluated.
Highlights
Free radical copolymerization is a valuable tool for tailoring the properties of polymeric materials for a broad range of applications
Copolymerization reactions of varying compositions of monomers[methyl methacrylate (MMA)/EOEMA: (A) 25:75, (B) 33.3:66.7, (C) 50:50, (D) 66.7:33.3, (E) 75:25] were carried out in 1,4-dioxane solvent at 60°C under the inert nitrogen atmosphere (Scheme I) For each reaction, calculated amounts of 2-Ethoxyethyl methacrylate (2-EOEMA), MMA, 1,4-dioxane and 0.5% AIBN were taken in a 250 mL three-necked round bottom flask, placed in an oil bath maintained at 60°C with continuous stirring
A strong absorption peak at 1731.7 cm-1 is due to the carbonyl ester group of MMA and 2-EOEMA units of the polymer
Summary
Free radical copolymerization is a valuable tool for tailoring the properties of polymeric materials for a broad range of applications. The MMA based polymers have good biocompatibility, low toxicity, good film forming and adhesive characteristics[13] It is used as a comonomer in surface-active copolymerization mainly because of its good amphilic character[8,9]. Methyl methacrylate and acrylate based copolymers are extensively studied by many investigators in biomedical applications such as membranes for ultra filtration/drug delivery, contact lenses and anticoagulant films[13]. The present investigation describes the synthesis of the MMA/EOEMA copolymer by free-radical polymerization and the polymer structure was characterized by IR, 1H-NMR and 13C-NMR spectroscopic techniques. Reactivity ratios calculated using the IR data are in good agreement with each other
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