October 1, 2017.
Polyhedral Oligomeric Silsesquioxane, often referred to as POSS, is an important type of nanostructured chemical compound because of its properties which bridge the gap between ceramic and organic materials. POSS has a variety of applications as an additive, a plastic, as well as a preceramic. Some more detailed examples of these categories are thermal modifiers when used as an additive, medical material when used as a plastic, and cladding or electronic coating when used as a preceramic. The two main valuable features of POSS chemical technology are how large the molecule building block is and what the intermediate composition is between SiO2 and R2SiO. Such information is crucial in POSS design and synthesis. Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS) is used to study POSS to provide more insight in its molecular structure and functioning group. Four POSS samples with different Si-O bond and functioning groups were analyzed. SIMS is widely used to analyze the surfaces by exposing the surface of the specimen with a primary focused ion beam and then analyzing the secondary ions which were ejected. POSS powder samples were analyzed in this study. Both positive ion and negative ion spectral plots were analyzed to obtain a more thorough understanding of characteristic peaks of the POSS samples. Peaks were then identified by searching for compounds masses and the intensity of these peaks reconfirmed the existence of that compound in the examined sample. The results of this comparative analysis revealed that each POSS sample had unique molecular fragments indicative of its structure and building block. Spectral principal component analysis (PCA) was conducted to identify the key peaks differentiating these samples. Our initial SIMS analysis demonstrates that useful structural information can be gained using SIMS.
Pacific Northwest National Laboratory (PNNL)
The 2017 STEM Teacher and Researcher Program and this project have been made possible through support from Chevron (www.chevron.com), the National Marine Sanctuary Foundation (www.marinesanctuary.org), the California State University Office of the Chancellor, and California Polytechnic State University, in partnership with Pacific Northwest National Laboratory.