Michele Cassetta, Herwig Peterlik, Thomas Konegger, Nicola Daldosso, Gian Domenico Sorarù, Mattia Biesuz
{"title":"在不同气氛中热解的聚合物二氧化硅玻璃的微孔演变","authors":"Michele Cassetta, Herwig Peterlik, Thomas Konegger, Nicola Daldosso, Gian Domenico Sorarù, Mattia Biesuz","doi":"10.1111/jace.19816","DOIUrl":null,"url":null,"abstract":"<p>Polymer-derived ceramics (PDCs) are a class of advanced materials obtained by pyrolysis in a controlled atmosphere of an organosilicon polymer. Their functional as well as mechanical properties originate from the peculiar nanostructures developed during the pyrolysis. Herein, we investigate the formation of transient microporosity in a model PDC (methyl-silsesquioxane) obtained in Ar, Ar–5%H<sub>2</sub>, CO<sub>2</sub>, and air. It is shown that a common evolution can be detected up to 700°C. At this temperature, the structure of the material in terms of chemical bonds is marginally changed (only redistribution reactions take place), but the medium-range order is clearly modified moving the system to a more disordered state (detected by small angle x-ray scattering [SAXS]) and causing the formation of a large amount of open micropores sized at about 1.2–1.7 nm. In the 700–800°C range, the proper ceramization starts causing the formation of a new class of small (around 1 nm) open micropores. These partially annihilate at 900°C in Ar and Ar–H<sub>2</sub> (i.e., in the second part of the ceramization process), whereas they totally collapse in CO<sub>2</sub> due to the formation of a more silica-like SiOC (less polymerized and viscous). Finally, SAXS points out the persistence of relatively large closed nanovoids of about 1 nm at 1250°C for the samples treated in Ar and Ar–H<sub>2</sub>. These might explain anomalies in terms of density, elastic modulus, and thermal conductivity of this class of ceramics as reported in the literature.</p>","PeriodicalId":200,"journal":{"name":"Journal of the American Ceramic Society","volume":null,"pages":null},"PeriodicalIF":3.5000,"publicationDate":"2024-04-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Microporosity evolution in polymer-derived SiOC glasses pyrolyzed in different atmospheres\",\"authors\":\"Michele Cassetta, Herwig Peterlik, Thomas Konegger, Nicola Daldosso, Gian Domenico Sorarù, Mattia Biesuz\",\"doi\":\"10.1111/jace.19816\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>Polymer-derived ceramics (PDCs) are a class of advanced materials obtained by pyrolysis in a controlled atmosphere of an organosilicon polymer. Their functional as well as mechanical properties originate from the peculiar nanostructures developed during the pyrolysis. Herein, we investigate the formation of transient microporosity in a model PDC (methyl-silsesquioxane) obtained in Ar, Ar–5%H<sub>2</sub>, CO<sub>2</sub>, and air. It is shown that a common evolution can be detected up to 700°C. At this temperature, the structure of the material in terms of chemical bonds is marginally changed (only redistribution reactions take place), but the medium-range order is clearly modified moving the system to a more disordered state (detected by small angle x-ray scattering [SAXS]) and causing the formation of a large amount of open micropores sized at about 1.2–1.7 nm. In the 700–800°C range, the proper ceramization starts causing the formation of a new class of small (around 1 nm) open micropores. These partially annihilate at 900°C in Ar and Ar–H<sub>2</sub> (i.e., in the second part of the ceramization process), whereas they totally collapse in CO<sub>2</sub> due to the formation of a more silica-like SiOC (less polymerized and viscous). Finally, SAXS points out the persistence of relatively large closed nanovoids of about 1 nm at 1250°C for the samples treated in Ar and Ar–H<sub>2</sub>. These might explain anomalies in terms of density, elastic modulus, and thermal conductivity of this class of ceramics as reported in the literature.</p>\",\"PeriodicalId\":200,\"journal\":{\"name\":\"Journal of the American Ceramic Society\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":3.5000,\"publicationDate\":\"2024-04-09\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of the American Ceramic Society\",\"FirstCategoryId\":\"88\",\"ListUrlMain\":\"https://onlinelibrary.wiley.com/doi/10.1111/jace.19816\",\"RegionNum\":3,\"RegionCategory\":\"材料科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"MATERIALS SCIENCE, CERAMICS\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of the American Ceramic Society","FirstCategoryId":"88","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1111/jace.19816","RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"MATERIALS SCIENCE, CERAMICS","Score":null,"Total":0}
Microporosity evolution in polymer-derived SiOC glasses pyrolyzed in different atmospheres
Polymer-derived ceramics (PDCs) are a class of advanced materials obtained by pyrolysis in a controlled atmosphere of an organosilicon polymer. Their functional as well as mechanical properties originate from the peculiar nanostructures developed during the pyrolysis. Herein, we investigate the formation of transient microporosity in a model PDC (methyl-silsesquioxane) obtained in Ar, Ar–5%H2, CO2, and air. It is shown that a common evolution can be detected up to 700°C. At this temperature, the structure of the material in terms of chemical bonds is marginally changed (only redistribution reactions take place), but the medium-range order is clearly modified moving the system to a more disordered state (detected by small angle x-ray scattering [SAXS]) and causing the formation of a large amount of open micropores sized at about 1.2–1.7 nm. In the 700–800°C range, the proper ceramization starts causing the formation of a new class of small (around 1 nm) open micropores. These partially annihilate at 900°C in Ar and Ar–H2 (i.e., in the second part of the ceramization process), whereas they totally collapse in CO2 due to the formation of a more silica-like SiOC (less polymerized and viscous). Finally, SAXS points out the persistence of relatively large closed nanovoids of about 1 nm at 1250°C for the samples treated in Ar and Ar–H2. These might explain anomalies in terms of density, elastic modulus, and thermal conductivity of this class of ceramics as reported in the literature.
期刊介绍:
The Journal of the American Ceramic Society contains records of original research that provide insight into or describe the science of ceramic and glass materials and composites based on ceramics and glasses. These papers include reports on discovery, characterization, and analysis of new inorganic, non-metallic materials; synthesis methods; phase relationships; processing approaches; microstructure-property relationships; and functionalities. Of great interest are works that support understanding founded on fundamental principles using experimental, theoretical, or computational methods or combinations of those approaches. All the published papers must be of enduring value and relevant to the science of ceramics and glasses or composites based on those materials.
Papers on fundamental ceramic and glass science are welcome including those in the following areas:
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Materials design, selection, synthesis and processing methods[...]
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