Reactivity ratios determination and NMR characterization of 2-hydroxy ethyl methacrylate and methyl methacrylate copolymers

NMR has proven to be one of the most informative technique for the investigation of copolymer microstructure as chemical shifts are sensitive to compositional and configurational sequences of copolymers. The HEMA/MMA copolymers were prepared by free radical bulk polymerization at 70 degrees C. The copolymer composition was determined from H-1 NMR spectrum which is then used to determine the reactivity ratios. The reactivity ratios obtained from KT, EVM and least square methods are r(HEMA) = 0.98, r(MMA) = 0.82; r(HEMA) = 0.88, r(MMA) = 0.81 and r(HEMA) = 0.92, r(MMA) = 0.81 respectively. H-1 and C-13{H-1} NMR spectra were analyzed with the help of DEPT, 2D HSQC and 2D TOCSY spectrum. The long range interactions of carbonyl carbon with methoxy protons and oxy methylene carbon with hydroxyl proton were determined with the help of heteronuclear multiple bond coherence (HMBC) spectrum. With the help of 2D spectra it was found that carbonyl, alpha-methyl and quaternary carbon of HEMA and MMA unit were sensitive to various configurational sequences as in poly(2-hydroxy ethyl methacrylate) and poly(methyl methacrylate). The carbonyl and oxymethylene carbons showed long range interactions with methoxy and hydroxyl protons respectively.