(604b) 1H-NMR Trajectories for Analyzing the Growth and Purification of 2D Polyaramids

The recent synthesis of two dimensional (2D) polyaramid (PA) polymers has shown that they exhibit remarkable mechanical and gas barrier properties. However, accurately measuring discoidal sizes of 2D polyaramids and tracking their growth over time remain challenging. Herein, we employ ¹H-NMR peak analysis of the aromatic and proton end group regions to characterize 2D-PA growth from monomeric precursors, alongside purification using a two-stage filtration and washing steps. The ratio of aromatic-to-end group protons serves as a metric for molecular weight and discoidal size, while the skewness of the NMR peaks in aromatic region provides a relative weighting between dendric small polycyclic intermediates and larger polycyclic domains. These two metrics delineate a two-dimension trajectory that proves valuable in analyzing the results of differing synthetic and processing conditions. Theoretical analysis of ideal dendrimer and polycyclic limits as a function of repeat unit size are derived as an aid in trajectory analysis. These results establish an analytical framework for evaluating 2D-PA and their variants, facilitating exploration of the synthetic landscape.