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首页> 外文期刊>Microporous and mesoporous materials: The offical journal of the International Zeolite Association >Direct synthesis of mesoporous silica presenting large and tunable pores using BAB triblock copolymers: Influence of each copolymer block on the porous structure
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Direct synthesis of mesoporous silica presenting large and tunable pores using BAB triblock copolymers: Influence of each copolymer block on the porous structure

机译：使用BAB三嵌段共聚物直接合成具有大孔和可调孔的介孔二氧化硅：每种共聚物嵌段对多孔结构的影响

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摘要

Mesoporous silicas with large and tunable (from 4 to 40 nm) accessible pores have been successfully synthesized using laboratory-made BAB (A: hydrophilic block, B: hydrophobic block) type triblock copolymers as templates. A direct synthesis is carried out in the absence of swelling agent and without any further treatment. The polystyrene-b-poly(ethylene oxide)-b-polystyrene (PS-b-PEO-b-PS) copolymers were synthesized using living/controlled radical polymerization. The porous structure (mesopore size, size distribution and microporous volume) was characterized using electron transmission microscopy and nitrogen sorption measurements. This study is focused on the control of the porous structure as a function of the hydrophobic PS block length and the hydrophilic block length (whilst keeping the other block length constant). It was found that when the PS block length increases: (i) the mesopore size increases linearly with PS block length which thus proffers a fine tuning of the pore diameter from 4 to 40 nm, (ii) the micropore volume decreases. When the PEO block length increases, (i) the mesopore size decreases (ii) the micropore volume increases. All these results were explained considering (i) that both PS and PEO block lengths have an influence on the degree of stretching of the PS chains, thus on the micellar core radius (ii) that the mesopore size is directly connected to the micellar core radius, i.e. that PEO chains do not directly participate to mesoporosity (due to its particular loop configuration) but only to microporosity.
机译：使用实验室制造的BAB（A：亲水性嵌段，B：疏水性嵌段）型三嵌段共聚物作为模板，成功合成了具有大孔和可调孔（4至40 nm）的中孔二氧化硅。在没有溶胀剂且没有任何进一步处理的情况下进行直接合成。使用活性/受控自由基聚合合成聚苯乙烯-b-聚（环氧乙烷）-b-聚苯乙烯（PS-b-PEO-b-PS）共聚物。使用电子透射显微镜和氮吸附测量来表征多孔结构（中孔尺寸，尺寸分布和微孔体积）。这项研究的重点是作为疏水性PS嵌段长度和亲水性嵌段长度（同时保持其他嵌段长度不变）的函数对多孔结构的控制。已经发现，当PS嵌段长度增加时：（i）中孔尺寸随PS嵌段长度线性增加，因此使孔径从4nm微调到40nm，（ii）微孔体积减小。当PEO嵌段长度增加时，（i）中孔尺寸减小（ii）微孔体积增加。考虑到所有这些结果，考虑到（i）PS和PEO嵌段长度均对PS链的拉伸程度有影响，因此对胶束核心半径有影响（ii）中孔尺寸直接与胶束核心半径有关即PEO链不直接参与介孔（由于其特殊的环状结构），而仅参与微孔。

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