A New Approach toward Investigation of Structure of Terminal Units of Poly(1,3-Pentadiene) using T2-Filtered NMR Spectroscopy

A new method for the identification of the structure of terminal units in poly(1,3‐pentadiene) synthesized by cationic mechanism is developed. The conducting of NMR experiments with a T₂ filter allows the intensities of the spectral signals of carbon and hydrogen atoms of main chain groups of poly(1,3‐pentadiene) with a short relaxation time to be decreased and significantly increases the intensities of signals of carbon and hydrogen atoms of head and end groups, which are characterized by higher mobility. Using 1D NMR spectroscopy with a T₂ filter as well as 2D heteronuclear single‐quantum correlation and heteronuclear multiple‐bond correlation NMR spectroscopy, it is found that the position of four out of five carbon atoms of the head group fully coincides with the position of spectral signals of carbon atoms of trans‐1,2‐ and trans‐1,4‐ units of a main polymer chain. This new method allows the identification of the signals of all carbon atoms in head trans‐1,4‐ group of poly(1,3‐pentadiene).