Polymer versus Monomer Action on the Growth and Habit Modification of Sodium Chloride Crystals

We have investigated the use of polymers and monomers as habit modifiers and anticaking agents for sodium chloride. We show that amide functional groups cause the {111} faces to propagate on sodium chloride crystals and that polymer amides give a 1–2 orders of magnitude greater effect than the corresponding monomers on the habit modification of sodium chloride. We have also shown that the alcohol functional group does not have an effect on the surface or habit modification but that, when in a polymer form, leads to macrostep formation and acts as a nucleation inhibitor. The latter also holds true for other polymers that we have also tested. We have also found that there is no evidence of these polymers having anticaking abilities. Finally, we found that no amino acids, apart from glycine, have an effect on the morphology of NaCl crystals.