Nanocellular Structures in Block Copolymers with CO2-philic Blocks Using CO2 as a Blowing Agent: Crossover from Micro- to Nanocellular Structures with Depressurization Temperature
Nanocellular Structures in Block Copolymers with CO2-philic Blocks Using CO2 as a Blowing Agent: Crossover from Micro- to Nanocellular Structures with Depressurization Temperature
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DOI：
10.1021/ma051757j
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发表时间：
2005-11
期刊：
影响因子：
5.5
通讯作者：
Hideaki Yokoyama;K. Sugiyama
中科院分区：
文献类型：
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作者：
Hideaki Yokoyama;K. Sugiyama
使用超临界（SC）二氧化碳（CO2），在聚[苯乙烯-嵌段-4-（全氟辛基丙氧基）苯乙烯]（PS-PFS）和聚[苯乙烯-嵌段-全氟辛基乙基甲基丙烯酸酯]（PS-PFMA）整体材料中的亲CO2氟化嵌段的球形纳米域内成功形成均匀的纳米细胞结构。纳米细胞具有非常小的表面积，表明其具有闭孔结构。减压温度 (Td) 是亲 CO2 嵌段纳米域中均匀纳米细胞形成的关键：Td 必须远低于 CO2 存在下骨架 PS 域的玻璃化转变温度 (Tg)。随着Td升高并接近Tg，纳米孔结构转变为微米量级的微孔结构，这是通过传统发泡机制形成的典型孔结构。当 Td 位于 Tg 附近时，两种独立的细胞形成机制共存。纳米细胞的上限直径为约。 40 nm，这显然是确定的......
Uniform nanocellular structures are successfully formed within the spherical nanodomains of CO2-philic fluorinated blocks in Poly[styrene-block-4-(perfluorooctylpropyloxy)styrene] (PS−PFS) and Poly[styrene-block-perfluorooctylethyl methacrylate] (PS−PFMA) monoliths using supercritical (SC) carbon dioxide (CO2). The nanocells have a very small surface area, indicative of the closed cell structure. Temperature of depressurization (Td) is the key to the uniform nanocellular formation in the CO2-philic block nanodomains: Td must be well below the glass transition temperature (Tg) of the skeleton PS domains in the presence of CO2. As Td is raised and approaches Tg, the nanocellular structure crosses over to the microcellular structure on the order of micrometers, which is the typical cell structure formed via the conventional foaming mechanism. Two independent cell formation mechanisms coexist when Td is in the vicinity of Tg. The nanocells have upper limit diameter of ca. 40 nm, which is apparently determine...