Chiral discrimination by a cellulose polymer: differential crystallization inhibition of enantiomers in amorphous dispersions

With the goal of better understanding how polymers inhibit crystallization in amorphous solid dispersions, crystal growth rates of the R and S enantiomers of a model chiral compound in the presence of chiral and achiral polymers were evaluated. The crystal growth rates of enantiomers in undercooled melts were inhibited to different extents by the same mass fraction of a chiral polymer, hydroxypropylmethyl cellulose acetate succinate. This is most likely due to differences in the ability of each enantiomer to form hydrogen bonding interactions with the polymer, which in turn impacts the crystallization behavior of the low molecular weight organic compound. In contrast, the achiral polymer polyvinylpyrrolidone, and the chiral polymer, hydroxypropylmethylcellulose phthalate showed the same inhibitory impact on each enantiomer.