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Polymorphs refer to substances that share the same chemical composition but are arranged in different crystal structures, leading to variations in their physical and chemical properties. This characteristic has significant implications for industries that seek to produce specific polymorphs, as different forms can result in divergent functionalities. Researchers at Tohoku University have explored the intricacies of colloidal crystallization to enable precise control over the formation of targeted polymorphs.
Upon examining a crystal under microscopic scrutiny, one can observe its distinct ordered arrangement. Colloidal crystals, which incorporate suspended particles smaller than a micron, exhibit this ordered structure, serving as effective models for phase transitions. These versatile materials have potential applications across diverse scientific and industrial sectors. Yet, the fundamental processes underlying the selection of polymorphs during crystallization remain largely elusive. One of the primary objectives of this research was to shed light on these mechanisms.
According to Jun Nozawa from Tohoku University, “Controlling the growth of specific crystal polymorphs is vital in areas such as materials science and pharmaceuticals. Alterations in polymorphs can lead to changes in the performance and functionality of products, so the ability to reliably select a specific polymorph is essential.”
The study employed colloidal crystallization as a model and utilized in situ observations with single-particle resolution to delve into the mechanisms behind polymorph selection. The researchers applied a technique known as heteroepitaxial growth involving polystyrene colloidal particles. Their investigation encompassed the key phases of crystallization: nucleation, growth, and dissolution, all of which were influenced by polymorphic transitions.
The findings indicated that the final products of the crystallization process were determined by these polymorph transitions, highlighting that the likelihood of a specific polymorph forming is influenced by particle size and the stability of clusters formed during the process. Additionally, the inclusion of particle additives proved effective in manipulating the formation of polymorphs.
Nozawa notes, “The factors we have studied can potentially guide the creation of the desired polymorphs depending on the context. This research paves the way for advancements in polymorph regulation technologies.”
This work enhances our understanding of how to exert control over polymorphs and provides valuable insights for applications in material manufacturing and pharmaceutical development. The results underscore the importance of cluster dynamics and growth rates in the selection of polymorphic crystals, going beyond the conventional focus on thermodynamic stability.
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