ESI-MS & MS/MS analysis of poly(2-oxazoline)s with different side groups

ESI-Q-TOF MS has been used for the detailed characterization of various poly(2-oxazoline)s with different side groups (i.e. methyl, ethyl, 1-ethylpentyl, phenyl, o-difluorophenyl and p-tert-butylphenyl) to evaluate this method as structural characterization tool for the detailed analysis of poly(2-oxazoline)s. The results obtained provided an understanding of the fragmentation of poly(2-oxazoline)s, revealing the elimination of small molecules such as ethene and hydrogen in their fragmentation patterns, which are partially dependent on the side groups. Also, a McLafferty rearrangement can be a possible fragmentation route for these polymers. In detail, side group elimination was only observed for poly(2-alkyl-2-oxazoline)s, but not for poly(2-aryl-2-oxazoline)s. ESI-Q-TOF MS was utilized to elucidate the structure of different poly(2-oxazoline)s prepared with the same initiating and end-groups in order to elucidate the effect of side groups on the fragmentation mechanism. 1,4-Hydrogen and ethene eliminations were observed for all poly(oxazoline)s, and a McLafferty rearrangement can be proposed as another fragmentation pathway. Side group elimination was only observed for poly(2-alkyl-2-oxazoline)s, in contrast to the investigated poly(2-aryl-2-oxazoline)s.