Synthesis, Structure and Dynamics of Block Copolymer Based Organic Inorganic Hybrid Materials

本研究将研究以有机改性陶瓷为前驱体的嵌段共聚纳米结构有机-无机杂化材料(ORMOCER)的合成、结构、结构形成和动态力学行为。为此，首先采用阴离子聚合的方法合成了聚异戊二烯-环氧乙烷(PI-b-PEO)两嵌段共聚物，其体积分数不同，分子量分布较窄。它们将作为结构导向剂，在两种金属醇盐混合物的溶胶-凝胶过程中，以不同的量添加到嵌段共聚物中。通过这种方法，将探索不同组成的PI-b-PEO两嵌段共聚物与无机材料混合的全相空间。重点是合成具有双连续回旋体形态的有机-无机杂化材料，这是嵌段共聚物中一种特别有趣的结构。所得到的结构将通过小角X射线散射(SAXS)和透射电子显微镜(TEM)测量进行分析。这一部分的结果将导致相图与两嵌段共聚物/均聚物混合物的相图相当。相图细节的分析将通过简单地通过溶解富含嵌段共聚物的大块样品来查看相图两相区域中的冻结的局部过渡区域的可能性而变得容易。此外，还将探索聚合物中的大变异性以及溶胶-凝胶化学来合成未知性能曲线的杂化材料。对于有机和无机前驱体混合物的特定组成，将使用原位SAXS研究加热下溶剂蒸发过程中的结构形成过程。通过将这些结果与硅和铝的固体核磁共振测量相关联，可以深入了解溶胶-凝胶化学和相分离之间的相互作用，以及最终形貌的途径。最后，本研究将允许系统地研究所得到的有机-无机杂化材料的动态力学行为。这些材料可以被视为理解具有重要商业意义的聚合物-粘土纳米复合材料的力学行为的模型系统。预计这项计划将促进对结构嵌段共聚物-二氧化硅杂化材料的形成机理和行为的基本理解的进步。同时，它将在聚合物科学和无机化学之间提供学生培训和学习。

In this research the synthesis, structure, structur-formation and dynamic mechanical behavior of block-copolymer-based, nano-structured organic-inorganic hybrid materials from organically modified ceramic (ORMOCER) precursors will be studied. To this end first a whole range of poly(isoprene-block ethyleneoxide) (PI-b-PEO) diblock copolymers with varying PEO volume fraction and narrow molecular weight distribution will be synthesized by anionic polymerization. These will be used as structure directing agents in the sol-gel process of a mixture of two metal alkoxides, added to the block copolymers in different amounts. In this way the full phase space for the mixture of PI-b-PEO diblock copolymers of various compositions with the inorganic materials will be explored. Special emphasis will be put on the synthesis of organic-inorganic hybrid materials with the bicontinuous gyroid morphology, a particularly interesting structure in block copolymers. The resulting structures will be analysed by small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM) measurements. Results of this part will lead to a phase diagram comparable to that of diblock copolymer/homopolymer mixtures. Analysis of details of the phase diagram will be facilitated by the possibility to look at frozen-in, local transition domains in biphasic regions of the phase diagram simply by dissolution of block copolymer rich bulk samples. Furthermore, the large variability in the polymer as well as the sol-gel chemistry will be explored to synthesize hybrid materials with unknown property profiles. For particular compositions of the mixtures of organic and inorganic precursors the structure formation process during evaporation of the solvent under heating will be investigated using in-situ SAXS. By correlating these results with solid-state NMR measurements on silicon and aluminum, insights into the interplay between sol-gel chemistry and phase separation as well as into the pathways towards the final morphologies will be obtained. Finally, the present study will allow for a systematic investigation of the dynamic mechanical behavior of the resulting organic-inorganic hybrid materials. These materials can be looked at as model systems for the understanding of the mechanical behavior of commercially important polymer-clay nanocomposites. It is expected that this program will lead to advances in the fundamental understanding of the mechanisms of formation and behavior of structured block copolymer-silica hybrid materials. At the same time it will provide student training and learning at the interface between polymer science and inorganic chemistry.