The researchers modeled the surfaces of ettringite, a key crystalline phase in the setting process, to establish the interaction of these surfaces with the phosphonate molecules typically used as cement retarders. Although these chemicals control the setting rate of the cement, their action is poorly understood, and new retarders have typically been discovered empirically. The modeling work helped the Schlumberger researchers to understand how phosphonates prevent growth of the ettringite phase by binding to particular crystal faces. More importantly, by identifying the salient geometric features, they were able to propose more effective inhibitors, which are now the subject of synthesis and testing. The final example brings us full circle, back to the pharmaceutical industry.
Drug discovery is just the start of the process of product development.
This is taken up by formulation chemists who take a molecule and find the best method of delivering it, often producing a finished crystalline form. Different polymorphs can have varying processibilities, densities, stabilities and, most significantly, therapeutic effects. Polymorph structures are conventionally determined by using single crystal X-ray diffraction, but often samples of the required purity cannot be crystallized. The experimental method also fails to guarantee that all possible polymorphs have been identified. MSI has developed a new computational method that predicts possible polymorphs starting from a model of the molecular structure.