Infrared spectra and thermal reactivity of ethene copolymers containing 1,2-cyclopropane units

A comparison between 13C NMR spectra of polymer solutions and Fourier transform infrared spectra of polymer films for several ethene-butadiene copolymers, including most butadiene as 1,2-cyclopropane and 1,2-cyclopentane units, is presented. This spectral comparison, also with the help of a low-molecular-mass model compound specifically synthesized for this purpose, has allowed to locate infrared absorbances associated with the cyclic comonomer units. In particular, a satisfactory calibration curve for evaluation of the amount of the reactive cyclopropane units, from the absorbance of the 1020 cm−1 band, has been achieved. An analysis of 1,2-cyclopropane unit reactivity in annealed films, has also pointed out that the presence of remnants of the polymerization catalyst can produce large increase in cyclopropane reactivity.