Influences of organometallic polymer‐derived catalyst dispersion on SWNT growth

Catalyst formation kinetics of a ferrocene‐containing homopolymer, polyferrocenylethylmethylsilane (PFEMS), is investigated as it relates to the catalysis of single walled carbon nanotubes (SWNTs) through a chemical vapor deposition (CVD) process. The formation and efficiency of the PFEMS‐based iron catalyst is compared with that of the corresponding polystyrene (PS)‐b‐PFEMS diblock copolymer. The PFEMS homopolymer contains 23 wt % iron, while PS‐b‐PFEMS, with a 25 vol % PFEMS content, is only 6% iron. Despite its lower iron content, spin‐cast PS‐b‐PFEMS films on SiO₂/Si substrates produce more active iron sites than spin‐cast PFEMS films during CVD growth of SWNTs. This is related to the self‐assembly of the block copolymer, where PFEMS domains are well dispersed in the PS matrix, which degrades at a CVD temperature of 920 °C to leave catalytically active elemental iron behind. On the contrary, the pure PFEMS films contain a high percentage of iron and silicon, which tend to transform into ceramic‐coated iron at this high temperature, thus rendering the iron inactive towards SWNT growth. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 758–765, 2007     

Organometallic-polypeptide block copolymers: synthesis and self-assembly of poly(ferrocenyldimethylsilane)-b-poly(epsilon-benzyloxycarbonyl-L-lysine)

A new type of metallopolymer-polypeptide block copolymer poly(ferrocenyldimethylsilane)-b-poly (epsilon-benzyloxycarbonyl-L-lysine) was synthesized by ring-opening polymerization of epsilon-benzyloxycarbonyl-L-lysine N-carboxyanhydride initiated by using a primary amino-terminated poly(ferrocenyldimethylsilane). Studies on the self-organization behavior of this polypeptide block copolymer in both the bulk state and in solution were performed. In the bulk state, a cylindrical-in-lamellar structure was observed in a compositionally asymmetric sample. Rod-like micelles with a polyferrocenylsilane core formed in a polypeptide-selective solvent alone or in the presence of a common solvent. Significantly, an additional small quantity of the common solvent assisted the formation of longer micelles and micelles with better shape-regularity. This is attributed to a decrease in the number of nucleation events and PFS core reorganization effects.     

聚二茂铁基硅烷二嵌段共聚物的制备、组装及应用研究

二茂铁分子由于含有独特的芳香结构和过渡金属元素铁,具有特殊的光、电、磁特性,一直以来是科学研究和技术应用的热点之一,在功能高分子材料的制备方面具有广泛的应用前景。聚二茂铁硅烷嵌段共聚物是一类新型的主链含有二茂铁和有机硅单元的聚合物,以其可控的分子量和丰富的自组装形貌,不断得到科研人员的关注。本文主要从聚合、自组装和应用三个方面系统介绍了聚二茂铁硅烷二嵌段共聚物。其中重点介绍了应用广泛的活性阴离子聚合和进一步发展起来的阴离子两步法聚合,解释了活性聚合机理,归纳了目前成功合成的不同种类的二嵌段共聚物;论述了在选择性溶剂中,聚二茂铁硅烷二嵌段共聚物可以自组装形成柱状、管状、球状等常规胶束和片层、刷形等复杂胶束,胶束的形成同聚合一样具有活性特征,并且在一定的刺激条件下,不同类型的胶束可完成相互转变过程,另外可以对胶束局部进行功能化以赋予其特殊的性能;最后介绍了聚二茂铁硅烷二嵌段共聚物在药物缓释、纳米材料、特种催化方面的具体实例,并对其应用前景加以展望。