Microstructure determination of poly(acrylonitrile-co-methyl methacrylate-co-methyl acrylate) terpolymers by 2D HMBC

A compositional and configurational sequence analysis from two-dimensional heteronuclear multiple bond correlation (HMBC) spectra of acrylonitrile/methyl methacrylate/methyl acrylate (A/B/M) terpolymer is being reported here. The methylene and methine carbon resonances assigned from 2D HSQC spectra were established by analyzing two and three bond order couplings with methyl, methylene and methine protons. α-Methyl carbon resonance of B-unit and methine carbon resonances of A- and M-unit were assigned up to triad compositional and configurational sequences while methylene carbon resonances were assigned up to tetrad compositional and configurational sequences. The assignments of carbonyl carbon resonances based on analysis of three bond couplings with methyl and methylene protons are reported. Quaternary carbon resonance of B-unit was assigned completely with the help of two bond order couplings with methyl and methylene protons. Both carbonyl and quaternary carbon resonances were found to be sensitive up to triad compositional and configurational sequences. Complete spectral assignment of quaternary and carbonyl carbon resonances showing the critical contribution of 2D HMBC spectra is indirect analysis of carbon resonances.