Tomoko Radomirovic

Phosphonate additives do not always inhibit crystallization

This paper investigates crystal growth modifiers based on 1,3,5-substituted benzene derivatives. The results show that as expected, the phosphonated derivative inhibits calcite precipitation to a much greater degree than the analogous sulfonate. However, on barium sulfate, both molecules show some crystallization promotion behaviour, with the phosphonate being the more potent promoter overall. Thus, the functional group alone does not determine the impact the organic molecule will have on crystallization. This opens the way for additives that have dual purposes (inhibiting the crystallization of one phase while not impacting or promoting the crystallization of other phases).

Small molecules induce mesocrystal formation: nanoparticle aggregation directed by self-assembling calixarenes

Calixarenes have been shown to induce mesocrystal formation of barium sulfate, despite being relatively low molecular weight additives. Scanning probe microscopy has shown that a possible mechanism is the self-assembling properties of the calixarene resulting in steric stabilization of the nanoparticles, comparable to that typically requiring polymeric additives.

Tetrazoles: a new class of compound for crystallization modification

Tetrazoles are a class of organic compound often used as carboxylic acid analogues. This analogous behaviour is shown to extend to crystallization modification, that is, tetrazoles are also able to influence crystal growth and morphology although in a different manner to their carboxylate counterparts. All the tetrazoles investigated thus far are shown to impact on barium sulfate and calcium carbonate crystallization to varying degrees. Thus, the tetrazoles represent a new class of crystal modifier.