Preparation and Morphology Control of Block Copolymer/Metal Salt Hybrids via Solvent-Casting by Using a Solvent with Coordination Ability

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• 作者：Atsushi Noro ; Yoshio Sageshima ; Shigeo Arai ; Yushu Matsushita
• 刊名：Macromolecules
• 出版年：2010
• 出版时间：June 22, 2010
• 年：2010
• 卷：43
• 期：12
• 页码：5358-5364
• 全文大小：899K
• 年卷期：v.43,no.12(June 22, 2010)
• ISSN：1520-5835

文摘

We report a systematic study on preparation and morphology control of macroscopically homogeneous hybrid films composed of a block copolymer and a metal salt, where one block interacts with a metal salt by metal-to-ligand coordination. Hybrids were prepared by blending a polystyrene-b-poly(4-vinylpyridine) (PS−P4VP, M_n=37K, _s=0.79) block copolymer and iron(III) chloride (FeCl₃) with changing the mole fraction of FeCl₃. To prevent the rapid cross-linking formation between P4VP and FeCl₃, pyridine as a polar solvent with the coordination ability was used at the solvent-casting stage, which turned out to be effective to prepare macroscopically homogeneous films with a large amount of FeCl₃. Transmission electron microscopy and small-angle X-ray scattering measurements were carried out to observe the morphology of thermally annealed samples at the nanoscopic scale. It was revealed that simple two-phase nanostructures were observed due to homogeneously mixing of FeCl₃ into a P4VP phase up to 0.9 mol equiv of FeCl₃ to pyridine units in P4VP. This indicates FeCl₃ works as a filler in a P4VP phase just as small homopolymers: domain expansion and morphology transition were observed as the amount of added FeCl₃ increases. However, overflow of FeCl₃ was observed in the hybrid with an amount of 1.0 mol equiv of FeCl₃. This is probably due to the saturation of incorporated FeCl₃, indicating that morphology of the present system can be controlled by stoichiometric balance between 4-vinylpyridine units and FeCl₃.