Tandem mass spectrometry (MS<sup>2</sup>) via collisionally activated dissociation (CAD), coupled with ion mobility (IM) separation, has been employed to determine the sequence of macrocyclic polyester copolymers with thermoresponsive properties. The polyesters were synthesized by polyesterification of succinic acid with two diols functionalized with different, bioinspired amide pendants. MS analysis confirmed the formation of cyclic and linear chains composed of two different polyester repeat units, N and P. MS<sup>2</sup> experiments on a sodiated homopolymeric trimer showed that fragmentation encompasses ring opening by 1,5-H rearrangement over an ester group and consecutive dissociation of the ring-opened species via the same mechanism. The sequence of the copolymeric tetramer N2P2 was elucidated based on the dimeric NN, NP (or PN), and PP fragments generated by CAD of the sodiated ion. The block architecture was found to predominate. The IM dimension enabled the examination of singly sodiated cyclic or linear chains that overlapped with higher charge states of larger oligomers. The sequencing strategy described in this study should be generally applicable to polymers with ester groups in the backbone. The architectural information deduced by such sequencing would significantly facilitate structure/property correlations and the design of copolymers with the desired physical properties.

Sequence analysis of cyclic thermoresponsive polyester copolymers using ion mobility tandem mass spectrometry

254th National Meeting (2017)

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