Unusual Stability of Amorphous Polymer Derived Ceramics at High Temperatures

这项工作的目标是发现SiCN-SiCO体系中PDCs的分子结构是如何使它们如此抵抗结晶和蠕变的。最近的SAXS研究表明存在1-3纳米大小的持久纳米结构域。然而，这些纳米结构域的化学和分子结构是未知的。它们是如何从有机聚合态进入陶瓷态的还不清楚。它们的形成热力学和界面热力学是未知的。为什么这些纳米结构域阻止结晶和蠕变尚不清楚。这些问题必须得到一致的、相互关联的回答。美德团队整合了NMR (D)、SAXS （US）、高温氧化溶液化学（US）、ab-initio分子建模(D)、无机合成与加工(D)、高温表征（US）等领域的专业知识，从根本上全面解决了这一关键问题。这个国际团队是一个自然的联盟，也是对德国科学家在这一领域早期发展中所发挥的重要作用的认可，以及最近美国人在研究聚合物衍生陶瓷的高温现象学方面的作用。

The objective of the proposed work is to discover what it is about the molecular structure of PDCs in the SiCN-SiCO system that renders them so resistant to crystallization and to creep. Recent SAXS studies have shown the presence of persistent nanodomains, 1-3 nm in size. However, the chemical and molecular constructions of these nanodomains are unknown. How they envolve from the organo-polymeric state into the ceramic state is not understood. Their thermodynamics of formation and interfacial energetics are unknown. Why these nanodomains preclude crystallization and creep is unclear. These questions must be answered in unison, and in relationship to each other. The US-German Team coalesces the expertise from NMR (D), SAXS (US), high temperature oxidative solution chemistry (US), ab-initio molecular modelling (D), inorganic synthesis and processing (D), and high temperature characterization (US), to solve this critical issue comprehensively and fundamentally. This international team is a natural coalition of, and also a recognition of the important role played be German scientists in the early developments of this field, and the recent role of the Americans in investigating the high temperature phenomenology of polymer-derived ceramics.