Siloxane polymers and silicone materials are major components in most people’s daily lives and are important in a wide variety of applications. However, despite their undeniable importance, they are often overlooked in the traditional undergraduate education, as they do not fall neatly into the traditional categories of organic or inorganic chemistry. Even in advanced polymer courses, they are often overlooked despite their value in describing many important polymer concepts. Herein we present three simple experiments to introduce siloxane polymers to the undergraduate education aimed at first-year, upper-level, and non-science-major students. This is prefaced with a brief overview of the history and chemistry of siloxanes and their value as teaching tools in the laboratory and classroom settings.
Magnesium powders are used widely in reactive and energetic composite materials, such as pyrotechnic formulations, solid fuels and explosives, as a vital ignition source. However, magnesium powders are highly reactive with atmospheric oxygen and moisture, forming the inert magnesium oxide and hydroxide. These reactions limit their shelf life, decrease their potency and affects the overall stability of these materials. In order to increase their long‐term stability, protective magnesium coatings are desired. In this work, a method for coating magnesium powders using tetramethylcyclotetrasiloxane (D4H) through a vapor‐solid interface reaction is described. This reaction requires no solvents, little material, and does not produce any corrosive byproducts. Coated powders demonstrate increased stability when exposed to elevated temperatures and high humidity conditions, with no oxidation of the magnesium observable. Despite improved stability, the coatings do not negatively impact ignition temperature and dynamics for magnesium powders.
The occlusion of dentinal tubules has become a rapid and effective method for treating dentin hypersensitivity. Accurate evaluation of dentin occlusion is critical to illustrate the efficacy of oral care products and to optimize dental therapy in the clinics, which is limited by the conventional two-dimensional (2-D) characterization methods. Here, we demonstrate the visualization of the dentin occlusion via three-dimensional (3-D) characterization using a focused ion beam-scanning electron microscopy (FIB-SEM) tomography. Using the “Slice and View” approach, the material used for occluding dentin tubules is imaged with a very high-resolution voxel (10 nm × 10 nm × 20 nm) from 2-D SEM images and then reconstructed into a 3-D volume, which presents the mode of action of toothpaste for treating dentin hypersensitivity. Meanwhile, quantitative analysis of the depth of occlusion is successfully obtained. This work validates the feasibility of FIB-SEM tomography in the analysis of dentin occlusion within the complicated networks of dentine tubules at the nanoscale, and provides a novel approach to facilitate the research and development of oral care products.
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