Silica-type mesostructures from block copolymer phases: Formation mechanism and generalization to the dense nanoparticle regime
Silica-type mesostructures from block copolymer phases: Formation mechanism and generalization to the dense nanoparticle regime
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DOI：
10.1021/ma0359786
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发表时间：
2004-07-27
期刊：
影响因子：
5.5
通讯作者：
Wiesner, U
中科院分区：
文献类型：
--
作者：
Jain, A;Wiesner, U
研究了以聚异戊二烯-嵌段-环氧乙烷两嵌段共聚物(PI-b-PEO)为结构导向剂的(3-缩水甘油氧丙基三甲氧基硅烷)和仲丁醇铝(Al(OBU)-Bu-S)杂化体系的局部结构和形成机理。PH测量、固体核磁共振、扫描力显微镜和力学性能分析结果表明，二氧化硅纳米粒子是缩合过程中的中间体，最终得到的复合材料在PEO/无机杂化结构域内表现出结构上的异质性。在实验结果的基础上，提出了聚合物-无机杂化形成的两步模型。在形成溶胶-凝胶纳米粒子并随后与嵌段共聚物混合后，进一步的缩合提供了概念上类似于在醇凝胶中观察到的局部非均相PEO/M有机结构域，但用PEO取代了溶剂。最后，讨论了与嵌段共聚物或其他两亲性化合物在高纳米颗粒密度区域工作对于产生新型纳米结构、功能聚合物-无机杂化材料的意义。
The present study elucidates the local structure and formation mechanism of a hybrid system based on poly(isoprene-block-ethylene oxide) diblock copolymers (PI-b-PEO) as structure directing agents for organically modified ceramic (ormocer) precursors, (3-glycidyloxypropyl)trimethoxysilane (GLYMO), and aluminum sec-butoxide (Al((OBu)-Bu-s)(3)). Employing results of pH measurements, solid-state NMR, scanning force microscopy, and mechanical properties analysis, it is shown that silica nanoparticles are an intermediate in the condensation process and that the final composites show structural heterogeneities within the PEO/inorganic containing domains of the hybrids. On the basis of the experimental results, a two-step model for the polymer-inorganic hybrid formation is developed. After sol-gel nanoparticle formation and subsequent mixing with the block copolymer, further condensation provides a locally heterogeneous PEO/morganic domain conceptually similar to what is observed in alcogels, but replacing the solvent by PEO. Finally, implications of working in the high nanoparticle density regime with block copolymers or other amphiphiles for the generation of novel nanostructured, functional polymer-inorganic hybrid materials are discussed.