Microstructure determination of 9-ethyl-3-hydroxymethylcarbazolyl acrylate/methacrylonitrile using two-dimensional NMR spectroscopy

Solution polymerization was carried out using AIBN as initiator at 60 °C and varying the molar infeed ratio to get different composition of 9-ethyl-3-hydroxymethylcarbazolyl acrylate-co-methacrylonitrile (C/N). The molecular weight was determined using gel-permeation chromatography (GPC). Differential scanning calorimetry (DSC) was used to determine the glass transition temperature (Tg). 13C{1H}, DEPT-45, 90 and 135 NMR techniques were used to distinguish the α-methyl, methine, backbone methylene and quaternary carbon resonance signals of C/N copolymers. Correlation of 1D (1H, 13C{1H}, DEPT) and 2D (HSQC, TOCSY, HMBC) NMR data were used to completely assign various overlapping and broad signals of C/N copolymers. Heteronuclear multi bond correlation (HMBC) studies were used to completely assign various nitrile resonances. The reactivity ratios calculated by Kelen–Tudos (KT) method were found to be rC = 0.31 ± 0.03 and rN = 0.80 ± 0.02 whereas those calculated from RREVM method were found to be rC = 0.35 and rN = 0.83, respectively.