The physical properties of hyperbranched polymers (HBPs) based on 2,2-bis(hydroxymethyl) propionic acid (bis-MPA), a monomer with a high concentration of hydroxyl groups, have been widely studied for their propensity to form hydrogen bonds (H-bonds). Similar studies and characterization have not yet been extended to bis-MPA based dendrimers due to the added synthetic efforts required. Despite these additional efforts, filling this intellectual gap is crucial to understanding the effects Hbonds have on the physical properties of these systems. Herein, hydrogen bond organization and interrelated structural order formation of a bis-MPA based dendrimers of the first through third generation (D1-3) were investigated via NMR, FTIR and WAXS. Hbond associations were found to decrease in strength as generation number increased (D1&gt;D2&gt;D3), while simultaneously, D2 showed the highest propensity for OH-OH Hbonds as opposed to OH-CO Hbonds. Since hydroxyls are capable of participating in either a donor or acceptor role, OH-OH Hbonds are capable of forming ‘chain-like’ associations of multiple Hbonds, carbonyls on the other hand are only capable of filling an acceptor role, limiting them to a single Hbond association. Molecular dynamics (MD) simulations were also used to predict the WAXS spectra and reveal these ‘chain-like’ associations of H-bonds. Dendrimers make a good candidate for simulations due to their uniform molecular distributions and lack of entanglements. Overall, computational results for these systems agree well with experimental data previously obtained for density and WAXS validating these systems.

Comparative Study of Hydrogen Bond Organization Between three generations of dendrimers based on bis-MPA

ACS Spring 2022

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